67 files changed, 1802 insertions, 856 deletions

diff --git a/src/Bindings/LuaState.cpp b/src/Bindings/LuaState.cpp
index 57c420795..7bd4becb6 100644
--- a/src/Bindings/LuaState.cpp
+++ b/src/Bindings/LuaState.cpp
@@ -1,4 +1,4 @@
-
+
 // LuaState.cpp
 
 // Implements the cLuaState class representing the wrapper over lua_State *, provides associated helper functions
diff --git a/src/Bindings/LuaState.h b/src/Bindings/LuaState.h
index 2e82c6994..98f1cbc28 100644
--- a/src/Bindings/LuaState.h
+++ b/src/Bindings/LuaState.h
@@ -1,4 +1,4 @@
-
+
 // LuaState.h
 
 // Declares the cLuaState class representing the wrapper over lua_State *, provides associated helper functions
diff --git a/src/Bindings/LuaWindow.cpp b/src/Bindings/LuaWindow.cpp
index ae390e576..2802c69db 100644
--- a/src/Bindings/LuaWindow.cpp
+++ b/src/Bindings/LuaWindow.cpp
@@ -54,15 +54,22 @@ cLuaWindow::~cLuaWindow()
 	m_Contents.RemoveListener(*this);
 
 	// Close open lua window from players, to avoid dangling pointers
-	cRoot::Get()->ForEachPlayer([this](cPlayer & a_Player)
+	class cPlayerCallback : public cPlayerListCallback
+	{
+		virtual bool Item(cPlayer * a_Player)
 		{
-			if (a_Player.GetWindow() == this)
+			if (a_Player->GetWindow() == m_LuaWindow)
 			{
-				a_Player.CloseWindow(false);
+				a_Player->CloseWindow(false);
 			}
 			return false;
 		}
-	);
+		cLuaWindow * m_LuaWindow;
+	public:
+		cPlayerCallback(cLuaWindow & a_LuaWindow) { m_LuaWindow = &a_LuaWindow; }
+	} PlayerCallback(*this);
+
+	cRoot::Get()->ForEachPlayer(PlayerCallback);
 
 	// Must delete slot areas now, because they are referencing this->m_Contents and would try to access it in cWindow's
 	// destructor, when the member is already gone.
diff --git a/src/Bindings/LuaWindow.h b/src/Bindings/LuaWindow.h
index 31891c7a3..8f3349d00 100644
--- a/src/Bindings/LuaWindow.h
+++ b/src/Bindings/LuaWindow.h
@@ -1,4 +1,4 @@
-
+
 // LuaWindow.h
 
 // Declares the cLuaWindow class representing a virtual window that plugins may create and open for the player
@@ -9,14 +9,13 @@
 
 #pragma once
 
-#include <functional>
 #include "LuaState.h"
 #include "../UI/Window.h"
 #include "../ItemGrid.h"
 
 
 class cPlayer;
-using cPlayerListCallback = std::function<bool(cPlayer &)>;
+typedef cItemCallback<cPlayer> cPlayerListCallback;
 
 
 /** A window that has been created by a Lua plugin and is handled entirely by that plugin
diff --git a/src/Bindings/ManualBindings.cpp b/src/Bindings/ManualBindings.cpp
index 5f8a3507d..38dc2cf83 100644
--- a/src/Bindings/ManualBindings.cpp
+++ b/src/Bindings/ManualBindings.cpp
@@ -1483,29 +1483,44 @@ static int tolua_cPluginManager_CallPlugin(lua_State * tolua_S)
 	}
 
 	// Call the destination plugin using a plugin callback:
-	int NumReturns = 0;
-	auto PluginCallback = [&](cPlugin & a_Plugin)
+	class cCallback :
+		public cPluginManager::cPluginCallback
+	{
+	public:
+		int m_NumReturns;
+
+		cCallback(const AString & a_FunctionName, cLuaState & a_SrcLuaState) :
+			m_NumReturns(0),
+			m_FunctionName(a_FunctionName),
+			m_SrcLuaState(a_SrcLuaState)
 		{
-			if (!a_Plugin.IsLoaded())
+		}
+	protected:
+		const AString & m_FunctionName;
+		cLuaState & m_SrcLuaState;
+
+		virtual bool Item(cPlugin * a_Plugin) override
+		{
+			if (!a_Plugin->IsLoaded())
 			{
 				return false;
 			}
-			NumReturns = static_cast<cPluginLua &>(a_Plugin).CallFunctionFromForeignState(
-				FunctionName, L, 4, lua_gettop(L)
+			m_NumReturns = static_cast<cPluginLua *>(a_Plugin)->CallFunctionFromForeignState(
+				m_FunctionName, m_SrcLuaState, 4, lua_gettop(m_SrcLuaState)
 			);
 			return true;
-		};
-
-	if (!cPluginManager::Get()->DoWithPlugin(PluginName, PluginCallback))
+		}
+	} Callback(FunctionName, L);
+	if (!cPluginManager::Get()->DoWithPlugin(PluginName, Callback))
 	{
 		return 0;
 	}
-	if (NumReturns < 0)
+	if (Callback.m_NumReturns < 0)
 	{
 		// The call has failed, there are zero return values. Do NOT return negative number (Lua considers that a "yield")
 		return 0;
 	}
-	return NumReturns;
+	return Callback.m_NumReturns;
 }
 
 
@@ -3228,29 +3243,42 @@ static int tolua_cRoot_DoWithPlayerByUUID(lua_State * tolua_S)
 		return 0;
 	}
 
+	class cCallback :
+		public cPlayerListCallback
+	{
+	public:
+		cCallback(cLuaState & a_LuaState) :
+			m_LuaState(a_LuaState)
+		{
+		}
+
+		virtual bool Item(cPlayer * a_Player) override
+		{
+			bool ret = false;
+			m_LuaState.Call(m_FnRef, a_Player, cLuaState::Return, ret);
+			return ret;
+		}
+
+		cLuaState & m_LuaState;
+		cLuaState::cRef m_FnRef;
+	} Callback(L);
+
 	// Get parameters:
 	cRoot * Self;
 	cUUID PlayerUUID;
-	cLuaState::cRef FnRef;
-	L.GetStackValues(1, Self, PlayerUUID, FnRef);
+	L.GetStackValues(1, Self, PlayerUUID, Callback.m_FnRef);
 
 	if (PlayerUUID.IsNil())
 	{
 		return L.ApiParamError("Expected a non-nil UUID for parameter #1");
 	}
-	if (!FnRef.IsValid())
+	if (!Callback.m_FnRef.IsValid())
 	{
 		return L.ApiParamError("Expected a valid callback function for parameter #2");
 	}
 
 	// Call the function:
-	bool res = Self->DoWithPlayerByUUID(PlayerUUID, [&](cPlayer & a_Player)
-		{
-			bool ret = false;
-			L.Call(FnRef, &a_Player, cLuaState::Return, ret);
-			return ret;
-		}
-	);
+	bool res = Self->DoWithPlayerByUUID(PlayerUUID, Callback);
 
 	// Push the result as the return value:
 	L.Push(res);
diff --git a/src/Bindings/ManualBindings.h b/src/Bindings/ManualBindings.h
index 64a44a240..dc9d9462f 100644
--- a/src/Bindings/ManualBindings.h
+++ b/src/Bindings/ManualBindings.h
@@ -1,4 +1,4 @@
-
+
 // ManualBindings.h
 
 // Declares the cManualBindings class used as a namespace for functions exported to the Lua API manually
@@ -57,7 +57,7 @@ public:
 	template <
 		class Ty1,
 		class Ty2,
-		bool (Ty1::*DoWithFn)(const AString &, const std::function<bool(Ty2 &)> &)
+		bool (Ty1::*DoWithFn)(const AString &, cItemCallback<Ty2> &)
 	>
 	static int DoWith(lua_State * tolua_S)
 	{
@@ -89,14 +89,28 @@ public:
 			return lua_do_error(tolua_S, "Error in function call '#funcname#': Expected a valid callback function for parameter #2");
 		}
 
-		// Call the DoWith function:
-		bool res = (Self->*DoWithFn)(ItemName, [&](Ty2 & a_Item)
+		class cLuaCallback : public cItemCallback<Ty2>
+		{
+		public:
+			cLuaCallback(cLuaState & a_LuaState, cLuaState::cRef & a_FnRef):
+				m_LuaState(a_LuaState),
+				m_FnRef(a_FnRef)
+			{
+			}
+
+		private:
+			virtual bool Item(Ty2 * a_Item) override
 			{
 				bool ret = false;
-				L.Call(FnRef, &a_Item, cLuaState::Return, ret);
+				m_LuaState.Call(m_FnRef, a_Item, cLuaState::Return, ret);
 				return ret;
 			}
-		);
+			cLuaState & m_LuaState;
+			cLuaState::cRef & m_FnRef;
+		} Callback(L, FnRef);
+
+		// Call the DoWith function:
+		bool res = (Self->*DoWithFn)(ItemName, Callback);
 
 		// Push the result as the return value:
 		L.Push(res);
@@ -111,7 +125,7 @@ public:
 	template <
 		class Ty1,
 		class Ty2,
-		bool (Ty1::*DoWithFn)(const AString &, const std::function<bool(Ty2 &)> &)
+		bool (Ty1::*DoWithFn)(const AString &, cItemCallback<Ty2> &)
 	>
 	static int StaticDoWith(lua_State * tolua_S)
 	{
@@ -138,14 +152,28 @@ public:
 			return lua_do_error(tolua_S, "Error in function call '#funcname#': Expected a valid callback function for parameter #2");
 		}
 
-		// Call the DoWith function:
-		bool res = (Ty1::Get()->*DoWithFn)(ItemName, [&](Ty2 & a_Item)
+		class cLuaCallback : public cItemCallback<Ty2>
+		{
+		public:
+			cLuaCallback(cLuaState & a_LuaState, cLuaState::cRef & a_FnRef):
+				m_LuaState(a_LuaState),
+				m_FnRef(a_FnRef)
+			{
+			}
+
+		private:
+			virtual bool Item(Ty2 * a_Item) override
 			{
 				bool ret = false;
-				L.Call(FnRef, &a_Item, cLuaState::Return, ret);
+				m_LuaState.Call(m_FnRef, a_Item, cLuaState::Return, ret);
 				return ret;
 			}
-		);
+			cLuaState & m_LuaState;
+			cLuaState::cRef & m_FnRef;
+		} Callback(L, FnRef);
+
+		// Call the DoWith function:
+		bool res = (Ty1::Get()->*DoWithFn)(ItemName, Callback);
 
 		// Push the result as the return value:
 		L.Push(res);
@@ -159,7 +187,7 @@ public:
 	template <
 		class Ty1,
 		class Ty2,
-		bool (Ty1::*DoWithFn)(UInt32, const std::function<bool(Ty2 &)> &)
+		bool (Ty1::*DoWithFn)(UInt32, cItemCallback<Ty2> &)
 	>
 	static int DoWithID(lua_State * tolua_S)
 	{
@@ -187,14 +215,28 @@ public:
 			return lua_do_error(tolua_S, "Error in function call '#funcname#': Expected a valid callback function for parameter #2");
 		}
 
-		// Call the DoWith function:
-		bool res = (Self->*DoWithFn)(ItemID, [&](Ty2 & a_Item)
+		class cLuaCallback : public cItemCallback<Ty2>
+		{
+		public:
+			cLuaCallback(cLuaState & a_LuaState, cLuaState::cRef & a_FnRef):
+				m_LuaState(a_LuaState),
+				m_FnRef(a_FnRef)
+			{
+			}
+
+		private:
+			virtual bool Item(Ty2 * a_Item) override
 			{
 				bool ret = false;
-				L.Call(FnRef, &a_Item, cLuaState::Return, ret);
+				m_LuaState.Call(m_FnRef, a_Item, cLuaState::Return, ret);
 				return ret;
 			}
-		);
+			cLuaState & m_LuaState;
+			cLuaState::cRef & m_FnRef;
+		} Callback(L, FnRef);
+
+		// Call the DoWith function:
+		bool res = (Self->*DoWithFn)(ItemID, Callback);
 
 		// Push the result as the return value:
 		L.Push(res);
@@ -209,7 +251,7 @@ public:
 	template <
 		class SELF,
 		class ITEM,
-		bool (SELF::*DoWithFn)(int, int, int, const std::function<bool(ITEM &)> &)
+		bool (SELF::*DoWithFn)(int, int, int, cItemCallback<ITEM> &)
 	>
 	static int DoWithXYZ(lua_State * tolua_S)
 	{
@@ -240,14 +282,28 @@ public:
 			return lua_do_error(tolua_S, "Error in function call '#funcname#': Expected a valid callback function for parameter #5");
 		}
 
-		// Call the DoWith function:
-		bool res = (Self->*DoWithFn)(BlockX, BlockY, BlockZ, [&](ITEM & a_Item)
+		class cLuaCallback : public cItemCallback<ITEM>
+		{
+		public:
+			cLuaCallback(cLuaState & a_LuaState, cLuaState::cRef & a_FnRef):
+				m_LuaState(a_LuaState),
+				m_FnRef(a_FnRef)
+			{
+			}
+
+		private:
+			virtual bool Item(ITEM * a_Item) override
 			{
 				bool ret = false;
-				L.Call(FnRef, &a_Item, cLuaState::Return, ret);
+				m_LuaState.Call(m_FnRef, a_Item, cLuaState::Return, ret);
 				return ret;
 			}
-		);
+			cLuaState & m_LuaState;
+			cLuaState::cRef & m_FnRef;
+		} Callback(L, FnRef);
+
+		// Call the DoWith function:
+		bool res = (Self->*DoWithFn)(BlockX, BlockY, BlockZ, Callback);
 
 		// Push the result as the return value:
 		L.Push(res);
@@ -262,7 +318,7 @@ public:
 	template <
 		class SELF,
 		class ITEM,
-		bool (SELF::*DoWithFn)(int, int, int, const std::function<bool(ITEM &)> &),
+		bool (SELF::*DoWithFn)(int, int, int, cItemCallback<ITEM> &),
 		bool (SELF::*CoordCheckFn)(int, int, int) const
 	>
 	static int DoWithXYZ(lua_State * tolua_S)
@@ -300,14 +356,28 @@ public:
 			).c_str());
 		}
 
-		// Call the DoWith function:
-		bool res = (Self->*DoWithFn)(BlockX, BlockY, BlockZ, [&](ITEM & a_Item)
+		class cLuaCallback : public cItemCallback<ITEM>
+		{
+		public:
+			cLuaCallback(cLuaState & a_LuaState, cLuaState::cRef & a_FnRef):
+				m_LuaState(a_LuaState),
+				m_FnRef(a_FnRef)
+			{
+			}
+
+		private:
+			virtual bool Item(ITEM * a_Item) override
 			{
 				bool ret = false;
-				L.Call(FnRef, &a_Item, cLuaState::Return, ret);
+				m_LuaState.Call(m_FnRef, a_Item, cLuaState::Return, ret);
 				return ret;
 			}
-		);
+			cLuaState & m_LuaState;
+			cLuaState::cRef & m_FnRef;
+		} Callback(L, FnRef);
+
+		// Call the DoWith function:
+		bool res = (Self->*DoWithFn)(BlockX, BlockY, BlockZ, Callback);
 
 		// Push the result as the return value:
 		L.Push(res);
@@ -321,7 +391,7 @@ public:
 	template <
 		class Ty1,
 		class Ty2,
-		bool (Ty1::*ForEachFn)(int, int, const std::function<bool(Ty2 &)> &)
+		bool (Ty1::*ForEachFn)(int, int, cItemCallback<Ty2> &)
 	>
 	static int ForEachInChunk(lua_State * tolua_S)
 	{
@@ -351,14 +421,28 @@ public:
 			return lua_do_error(tolua_S, "Error in function call '#funcname#': Expected a valid callback function for parameter #4");
 		}
 
-		// Call the DoWith function:
-		bool res = (Self->*ForEachFn)(ChunkX, ChunkZ, [&](Ty2 & a_Item)
+		class cLuaCallback : public cItemCallback<Ty2>
+		{
+		public:
+			cLuaCallback(cLuaState & a_LuaState, cLuaState::cRef & a_FnRef):
+				m_LuaState(a_LuaState),
+				m_FnRef(a_FnRef)
+			{
+			}
+
+		private:
+			virtual bool Item(Ty2 * a_Item) override
 			{
 				bool ret = false;
-				L.Call(FnRef, &a_Item, cLuaState::Return, ret);
+				m_LuaState.Call(m_FnRef, a_Item, cLuaState::Return, ret);
 				return ret;
 			}
-		);
+			cLuaState & m_LuaState;
+			cLuaState::cRef & m_FnRef;
+		} Callback(L, FnRef);
+
+		// Call the DoWith function:
+		bool res = (Self->*ForEachFn)(ChunkX, ChunkZ, Callback);
 
 		// Push the result as the return value:
 		L.Push(res);
@@ -372,7 +456,7 @@ public:
 	template <
 		class Ty1,
 		class Ty2,
-		bool (Ty1::*ForEachFn)(const cBoundingBox &, const std::function<bool(Ty2 &)> &)
+		bool (Ty1::*ForEachFn)(const cBoundingBox &, cItemCallback<Ty2> &)
 	>
 	static int ForEachInBox(lua_State * tolua_S)
 	{
@@ -404,19 +488,36 @@ public:
 			return lua_do_error(tolua_S, "Error in function call '#funcname#': Expected a valid callback function for parameter #2");
 		}
 
-		bool res = (Self->*ForEachFn)(*Box, [&](Ty2 & a_Item)
+		// Callback wrapper for the Lua function:
+		class cLuaCallback : public cItemCallback<Ty2>
+		{
+		public:
+			cLuaCallback(cLuaState & a_LuaState, cLuaState::cRef & a_FuncRef) :
+				m_LuaState(a_LuaState),
+				m_FnRef(a_FuncRef)
 			{
-				bool ret = false;
-				if (!L.Call(FnRef, &a_Item, cLuaState::Return, ret))
+			}
+
+		private:
+			cLuaState & m_LuaState;
+			cLuaState::cRef & m_FnRef;
+
+			// cItemCallback<Ty2> overrides:
+			virtual bool Item(Ty2 * a_Item) override
+			{
+				bool res = false;
+				if (!m_LuaState.Call(m_FnRef, a_Item, cLuaState::Return, res))
 				{
 					LOGWARNING("Failed to call Lua callback");
-					L.LogStackTrace();
+					m_LuaState.LogStackTrace();
 					return true;  // Abort enumeration
 				}
 
-				return ret;
+				return res;
 			}
-		);
+		} Callback(L, FnRef);
+
+		bool res = (Self->*ForEachFn)(*Box, Callback);
 
 		// Push the result as the return value:
 		L.Push(res);
@@ -430,7 +531,7 @@ public:
 	template <
 		class Ty1,
 		class Ty2,
-		bool (Ty1::*ForEachFn)(const std::function<bool(Ty2 &)> &)
+		bool (Ty1::*ForEachFn)(cItemCallback<Ty2> &)
 	>
 	static int ForEach(lua_State * tolua_S)
 	{
@@ -457,14 +558,29 @@ public:
 			return lua_do_error(tolua_S, "Error in function call '#funcname#': Expected a valid callback function for parameter #1");
 		}
 
-		// Call the enumeration:
-		bool res = (Self->*ForEachFn)([&](Ty2 & a_Item)
+		class cLuaCallback : public cItemCallback<Ty2>
+		{
+		public:
+			cLuaCallback(cLuaState & a_LuaState, cLuaState::cRef & a_FnRef):
+				m_LuaState(a_LuaState),
+				m_FnRef(a_FnRef)
 			{
-				bool ret = false;  // By default continue the enumeration
-				L.Call(FnRef, &a_Item, cLuaState::Return, ret);
-				return ret;
 			}
-		);
+
+		private:
+			cLuaState & m_LuaState;
+			cLuaState::cRef & m_FnRef;
+
+			virtual bool Item(Ty2 * a_Item) override
+			{
+				bool res = false;  // By default continue the enumeration
+				m_LuaState.Call(m_FnRef, a_Item, cLuaState::Return, res);
+				return res;
+			}
+		} Callback(L, FnRef);
+
+		// Call the enumeration:
+		bool res = (Self->*ForEachFn)(Callback);
 
 		// Push the return value:
 		L.Push(res);
@@ -479,7 +595,7 @@ public:
 	template <
 		class Ty1,
 		class Ty2,
-		bool (Ty1::*ForEachFn)(const std::function<bool(Ty2 &)> &)
+		bool (Ty1::*ForEachFn)(cItemCallback<Ty2> &)
 	>
 	static int StaticForEach(lua_State * tolua_S)
 	{
@@ -500,14 +616,29 @@ public:
 			return lua_do_error(tolua_S, "Error in function call '#funcname#': Expected a valid callback function for parameter #1");
 		}
 
-		// Call the enumeration:
-		bool res = (Ty1::Get()->*ForEachFn)([&](Ty2 & a_Item)
+		class cLuaCallback : public cItemCallback<Ty2>
+		{
+		public:
+			cLuaCallback(cLuaState & a_LuaState, cLuaState::cRef & a_FnRef):
+				m_LuaState(a_LuaState),
+				m_FnRef(a_FnRef)
 			{
-				bool ret = false;  // By default continue the enumeration
-				L.Call(FnRef, &a_Item, cLuaState::Return, ret);
-				return ret;
 			}
-		);
+
+		private:
+			cLuaState & m_LuaState;
+			cLuaState::cRef & m_FnRef;
+
+			virtual bool Item(Ty2 * a_Item) override
+			{
+				bool res = false;  // By default continue the enumeration
+				m_LuaState.Call(m_FnRef, a_Item, cLuaState::Return, res);
+				return res;
+			}
+		} Callback(L, FnRef);
+
+		// Call the enumeration:
+		bool res = (Ty1::Get()->*ForEachFn)(Callback);
 
 		// Push the return value:
 		L.Push(res);
diff --git a/src/Bindings/ManualBindings_World.cpp b/src/Bindings/ManualBindings_World.cpp
index 826439e3f..10b5daf1e 100644
--- a/src/Bindings/ManualBindings_World.cpp
+++ b/src/Bindings/ManualBindings_World.cpp
@@ -1,4 +1,4 @@
-
+
 // ManualBindings_World.cpp
 
 // Implements the manual Lua API bindings for the cWorld class
@@ -237,10 +237,10 @@ static int tolua_cWorld_DoWithPlayerByUUID(lua_State * tolua_S)
 	}
 
 	// Call the function:
-	bool res = Self->DoWithPlayerByUUID(PlayerUUID, [&](cPlayer & a_Player)
+	bool res = Self->DoWithPlayerByUUID(PlayerUUID, [&](cPlayer * a_Player)
 		{
 			bool ret = false;
-			L.Call(FnRef, &a_Player, cLuaState::Return, ret);
+			L.Call(FnRef, a_Player, cLuaState::Return, ret);
 			return ret;
 		}
 	);
diff --git a/src/Bindings/PluginManager.cpp b/src/Bindings/PluginManager.cpp
index 1b3736e3c..7c4712f0f 100644
--- a/src/Bindings/PluginManager.cpp
+++ b/src/Bindings/PluginManager.cpp
@@ -1,4 +1,4 @@
-
+
 #include "Globals.h"  // NOTE: MSVC stupidness requires this to be the same across all modules
 
 #include "PluginManager.h"
@@ -1993,14 +1993,14 @@ bool cPluginManager::IsValidHookType(int a_HookType)
 
 
 
-bool cPluginManager::DoWithPlugin(const AString & a_PluginName, const cPluginCallback & a_Callback)
+bool cPluginManager::DoWithPlugin(const AString & a_PluginName, cPluginCallback & a_Callback)
 {
 	// TODO: Implement locking for plugins
 	for (auto & plugin: m_Plugins)
 	{
 		if (plugin->GetName() == a_PluginName)
 		{
-			return a_Callback(*plugin);
+			return a_Callback.Item(plugin.get());
 		}
 	}
 	return false;
@@ -2010,12 +2010,12 @@ bool cPluginManager::DoWithPlugin(const AString & a_PluginName, const cPluginCal
 
 
 
-bool cPluginManager::ForEachPlugin(const cPluginCallback & a_Callback)
+bool cPluginManager::ForEachPlugin(cPluginCallback & a_Callback)
 {
 	// TODO: Implement locking for plugins
 	for (auto & plugin: m_Plugins)
 	{
-		if (a_Callback(*plugin))
+		if (a_Callback.Item(plugin.get()))
 		{
 			return false;
 		}
diff --git a/src/Bindings/PluginManager.h b/src/Bindings/PluginManager.h
index 4de4bdeae..66f7d290a 100644
--- a/src/Bindings/PluginManager.h
+++ b/src/Bindings/PluginManager.h
@@ -1,9 +1,8 @@
-
+
 #pragma once
 
 
 #include "Defines.h"
-#include <functional>
 
 
 
@@ -195,7 +194,7 @@ public:
 
 
 	/** The interface used for enumerating and extern-calling plugins */
-	using cPluginCallback = std::function<bool(cPlugin &)>;
+	typedef cItemCallback<cPlugin> cPluginCallback;
 
 	typedef std::list<cPlugin *> PluginList;
 
@@ -373,18 +372,18 @@ public:
 
 	/** Calls the specified callback with the plugin object of the specified plugin.
 	Returns false if plugin not found, otherwise returns the value that the callback has returned. */
-	bool DoWithPlugin(const AString & a_PluginName, const cPluginCallback & a_Callback);
+	bool DoWithPlugin(const AString & a_PluginName, cPluginCallback & a_Callback);
 
 	/** Calls the specified callback for each plugin in m_Plugins.
 	Returns true if all plugins have been reported, false if the callback has aborted the enumeration by returning true. */
-	bool ForEachPlugin(const cPluginCallback & a_Callback);
+	bool ForEachPlugin(cPluginCallback & a_Callback);
 
 	/** Returns the name of the folder (cPlugin::GetFolderName()) from which the specified plugin was loaded. */
 	AString GetPluginFolderName(const AString & a_PluginName);  // tolua_export
 
 	/** Returns the path where individual plugins' folders are expected.
 	The path doesn't end in a slash. */
-	static AString GetPluginsPath(void) { return FILE_IO_PREFIX "Plugins"; }  // tolua_export
+	static AString GetPluginsPath(void) { return FILE_IO_PREFIX + AString("Plugins"); }  // tolua_export
 
 private:
 	friend class cRoot;
diff --git a/src/BlockArea.cpp b/src/BlockArea.cpp
index 755d98583..667a231a4 100644
--- a/src/BlockArea.cpp
+++ b/src/BlockArea.cpp
@@ -1,4 +1,4 @@
-
+
 // BlockArea.cpp
 
 // NOTE: compile.sh checks for this file in order to determine if this is the Cuberite folder.
@@ -2239,7 +2239,7 @@ int cBlockArea::MakeIndex(int a_RelX, int a_RelY, int a_RelZ) const
 
 
 
-bool cBlockArea::DoWithBlockEntityRelAt(int a_RelX, int a_RelY, int a_RelZ, const cBlockEntityCallback & a_Callback)
+bool cBlockArea::DoWithBlockEntityRelAt(int a_RelX, int a_RelY, int a_RelZ, cItemCallback<cBlockEntity> & a_Callback)
 {
 	ASSERT(IsValidRelCoords(a_RelX, a_RelY, a_RelZ));
 	if (!HasBlockEntities())
@@ -2252,14 +2252,14 @@ bool cBlockArea::DoWithBlockEntityRelAt(int a_RelX, int a_RelY, int a_RelZ, cons
 	{
 		return false;
 	}
-	return a_Callback(*itr->second);
+	return a_Callback.Item(itr->second);
 }
 
 
 
 
 
-bool cBlockArea::DoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBlockEntityCallback & a_Callback)
+bool cBlockArea::DoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, cItemCallback<cBlockEntity> & a_Callback)
 {
 	return DoWithBlockEntityRelAt(a_BlockX - m_Origin.x, a_BlockY - m_Origin.y, a_BlockZ - m_Origin.z, a_Callback);
 }
@@ -2268,7 +2268,7 @@ bool cBlockArea::DoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, c
 
 
 
-bool cBlockArea::ForEachBlockEntity(const cBlockEntityCallback & a_Callback)
+bool cBlockArea::ForEachBlockEntity(cItemCallback<cBlockEntity> & a_Callback)
 {
 	if (!HasBlockEntities())
 	{
@@ -2276,7 +2276,7 @@ bool cBlockArea::ForEachBlockEntity(const cBlockEntityCallback & a_Callback)
 	}
 	for (auto & keyPair: *m_BlockEntities)
 	{
-		if (a_Callback(*keyPair.second))
+		if (a_Callback.Item(keyPair.second))
 		{
 			return false;
 		}
diff --git a/src/BlockArea.h b/src/BlockArea.h
index e7080ed88..2e35b9436 100644
--- a/src/BlockArea.h
+++ b/src/BlockArea.h
@@ -1,4 +1,4 @@
-
+
 // BlockArea.h
 
 // Interfaces to the cBlockArea object representing an area of block data that can be queried from cWorld and then accessed again without further queries
@@ -17,14 +17,13 @@
 #include "ForEachChunkProvider.h"
 #include "ChunkDataCallback.h"
 #include "Cuboid.h"
-#include <functional>
 
 
 
 
 // fwd:
 class cCuboid;
-using cBlockEntityCallback = std::function<bool(cBlockEntity &)>;
+
 
 
 
@@ -377,18 +376,18 @@ public:
 	/** Calls the callback for the block entity at the specified coords.
 	Returns false if there is no block entity at those coords, or the block area doesn't have baBlockEntities.
 	Returns the value that the callback has returned if there is a block entity. */
-	bool DoWithBlockEntityRelAt(int a_RelX, int a_RelY, int a_RelZ, const cBlockEntityCallback & a_Callback);
+	bool DoWithBlockEntityRelAt(int a_RelX, int a_RelY, int a_RelZ, cItemCallback<cBlockEntity> & a_Callback);
 
 	/** Calls the callback for the block entity at the specified coords.
 	Returns false if there is no block entity at those coords.
 	Returns the value that the callback has returned if there is a block entity. */
-	bool DoWithBlockEntityAt   (int a_BlockX, int a_BlockY, int a_BlockZ, const cBlockEntityCallback & a_Callback);
+	bool DoWithBlockEntityAt   (int a_BlockX, int a_BlockY, int a_BlockZ, cItemCallback<cBlockEntity> & a_Callback);
 
 	/** Calls the callback for all the block entities.
 	If the callback returns true, aborts the enumeration and returns false.
 	If the callback returns true, continues with the next BE.
 	Returns true if all block entities have been enumerated (including the case when there is none or the area is without baBlockEntities). */
-	bool ForEachBlockEntity(const cBlockEntityCallback & a_Callback);
+	bool ForEachBlockEntity(cItemCallback<cBlockEntity> & a_Callback);
 
 	/** Direct read-only access to block entities. */
 	const cBlockEntities & GetBlockEntities(void) const { ASSERT(HasBlockEntities()); return *m_BlockEntities; }
diff --git a/src/BlockEntities/BeaconEntity.cpp b/src/BlockEntities/BeaconEntity.cpp
index 1d088a56f..a98547ba7 100644
--- a/src/BlockEntities/BeaconEntity.cpp
+++ b/src/BlockEntities/BeaconEntity.cpp
@@ -1,4 +1,4 @@
-
+
 #include "Globals.h"  // NOTE: MSVC stupidness requires this to be the same across all modules
 
 #include "BeaconEntity.h"
@@ -195,21 +195,33 @@ void cBeaconEntity::UpdateBeacon(void)
 			GetWindow()->SetProperty(0, m_BeaconLevel);
 		}
 
-		Vector3d BeaconPosition(m_PosX, m_PosY, m_PosZ);
-		GetWorld()->ForEachPlayer([=](cPlayer & a_Player)
+		class cPlayerCallback :
+			public cPlayerListCallback
+		{
+		public:
+			cPlayerCallback(Vector3d a_Position):
+				m_Position(a_Position)
 			{
-				Vector3d Distance = BeaconPosition - a_Player.GetPosition();
+			}
+
+			virtual bool Item(cPlayer * a_Player)
+			{
+				Vector3d Distance = m_Position - a_Player->GetPosition();
 				if (
 					(std::abs(Distance.y) <= 14) &&
 					(std::abs(Distance.x) <= 20) &&
 					(std::abs(Distance.z) <= 20)
 				)
 				{
-					a_Player.AwardAchievement(eStatistic::achFullBeacon);
+					a_Player->AwardAchievement(eStatistic::achFullBeacon);
 				}
 				return false;
 			}
-		);
+
+		private:
+			Vector3d m_Position;
+		} PlayerCallback(Vector3d(m_PosX, m_PosY, m_PosZ));
+		GetWorld()->ForEachPlayer(PlayerCallback);
 	}
 }
 
@@ -237,28 +249,46 @@ void cBeaconEntity::GiveEffects(void)
 		SecondaryEffect = m_SecondaryEffect;
 	}
 
-	Vector3d BeaconPosition(m_PosX, m_PosY, m_PosZ);
-	GetWorld()->ForEachPlayer([=](cPlayer & a_Player)
+	class cPlayerCallback : public cPlayerListCallback
+	{
+		int m_Radius;
+		Vector3d m_Position;
+		cEntityEffect::eType m_PrimaryEffect, m_SecondaryEffect;
+		short m_EffectLevel;
+
+		virtual bool Item(cPlayer * a_Player)
 		{
-			auto PlayerPosition = a_Player.GetPosition();
-			if (PlayerPosition.y > BeaconPosition.y)
+			Vector3d PlayerPosition = Vector3d(a_Player->GetPosition());
+			if (PlayerPosition.y > m_Position.y)
 			{
-				PlayerPosition.y = BeaconPosition.y;
+				PlayerPosition.y = m_Position.y;
 			}
 
 			// TODO: Vanilla minecraft uses an AABB check instead of a radius one
-			if ((PlayerPosition - BeaconPosition).Length() <= Radius)
+			if ((PlayerPosition - m_Position).Length() <= m_Radius)
 			{
-				a_Player.AddEntityEffect(m_PrimaryEffect, 180, EffectLevel);
+				a_Player->AddEntityEffect(m_PrimaryEffect, 180, m_EffectLevel);
 
 				if (m_SecondaryEffect != cEntityEffect::effNoEffect)
 				{
-					a_Player.AddEntityEffect(m_SecondaryEffect, 180, 0);
+					a_Player->AddEntityEffect(m_SecondaryEffect, 180, 0);
 				}
 			}
 			return false;
 		}
-	);
+
+	public:
+		cPlayerCallback(int a_Radius, Vector3d a_Position, cEntityEffect::eType a_PrimaryEffect, cEntityEffect::eType a_SecondaryEffect, short a_EffectLevel):
+			m_Radius(a_Radius),
+			m_Position(a_Position),
+			m_PrimaryEffect(a_PrimaryEffect),
+			m_SecondaryEffect(a_SecondaryEffect),
+			m_EffectLevel(a_EffectLevel)
+		{
+		}
+
+	} PlayerCallback(Radius, Vector3d(m_PosX, m_PosY, m_PosZ), m_PrimaryEffect, SecondaryEffect, EffectLevel);
+	GetWorld()->ForEachPlayer(PlayerCallback);
 }
 
 
diff --git a/src/BlockEntities/ChestEntity.cpp b/src/BlockEntities/ChestEntity.cpp
index 5e8b29a45..a8f5b7242 100644
--- a/src/BlockEntities/ChestEntity.cpp
+++ b/src/BlockEntities/ChestEntity.cpp
@@ -138,18 +138,33 @@ bool cChestEntity::UsedBy(cPlayer * a_Player)
 void cChestEntity::ScanNeighbours()
 {
 	// Callback for finding neighbouring chest:
-	auto FindNeighbour = [this](cChestEntity & a_Chest)
+	class cFindNeighbour :
+		public cChestCallback
 	{
-		if (a_Chest.GetBlockType() != m_BlockType)
+	public:
+		cChestEntity * m_Neighbour;
+		BLOCKTYPE      m_ChestType;
+
+		cFindNeighbour(BLOCKTYPE a_ChestType) :
+			m_Neighbour(nullptr),
+			m_ChestType(a_ChestType)
 		{
-			// Neighboring block is not the same type of chest
-			return true;
 		}
-		m_Neighbour = &a_Chest;
-		return false;
+
+		virtual bool Item(cChestEntity * a_Chest) override
+		{
+			if (a_Chest->GetBlockType() != m_ChestType)
+			{
+				// Neighboring block is not the same type of chest
+				return true;
+			}
+			m_Neighbour = a_Chest;
+			return false;
+		}
 	};
 
 	// Scan horizontally adjacent blocks for any neighbouring chest of the same type:
+	cFindNeighbour FindNeighbour(m_BlockType);
 	if (
 		m_World->DoWithChestAt(m_PosX - 1, m_PosY, m_PosZ,     FindNeighbour) ||
 		m_World->DoWithChestAt(m_PosX + 1, m_PosY, m_PosZ,     FindNeighbour) ||
@@ -157,6 +172,7 @@ void cChestEntity::ScanNeighbours()
 		m_World->DoWithChestAt(m_PosX,     m_PosY, m_PosZ + 1, FindNeighbour)
 	)
 	{
+		m_Neighbour = FindNeighbour.m_Neighbour;
 		m_Neighbour->m_Neighbour = this;
 		// Force neighbour's window shut. Does Mojang server do this or should a double window open?
 		m_Neighbour->DestroyWindow();
diff --git a/src/BlockEntities/HopperEntity.cpp b/src/BlockEntities/HopperEntity.cpp
index 2fac188b1..0467685af 100644
--- a/src/BlockEntities/HopperEntity.cpp
+++ b/src/BlockEntities/HopperEntity.cpp
@@ -193,7 +193,8 @@ bool cHopperEntity::MovePickupsIn(cChunk & a_Chunk, Int64 a_CurrentTick)
 {
 	UNUSED(a_CurrentTick);
 
-	class cHopperPickupSearchCallback
+	class cHopperPickupSearchCallback :
+		public cEntityCallback
 	{
 	public:
 		cHopperPickupSearchCallback(const Vector3i & a_Pos, cItemGrid & a_Contents) :
@@ -203,20 +204,22 @@ bool cHopperEntity::MovePickupsIn(cChunk & a_Chunk, Int64 a_CurrentTick)
 		{
 		}
 
-		bool operator () (cEntity & a_Entity)
+		virtual bool Item(cEntity * a_Entity) override
 		{
-			if (!a_Entity.IsPickup())
+			ASSERT(a_Entity != nullptr);
+
+			if (!a_Entity->IsPickup())
 			{
 				return false;
 			}
 
-			Vector3f EntityPos = a_Entity.GetPosition();
+			Vector3f EntityPos = a_Entity->GetPosition();
 			Vector3f BlockPos(m_Pos.x + 0.5f, static_cast<float>(m_Pos.y) + 1, m_Pos.z + 0.5f);  // One block above hopper, and search from center outwards
 			double Distance = (EntityPos - BlockPos).Length();
 
 			if (Distance < 0.5)
 			{
-				if (TrySuckPickupIn(static_cast<cPickup &>(a_Entity)))
+				if (TrySuckPickupIn(static_cast<cPickup *>(a_Entity)))
 				{
 					return false;
 				}
@@ -225,9 +228,9 @@ bool cHopperEntity::MovePickupsIn(cChunk & a_Chunk, Int64 a_CurrentTick)
 			return false;
 		}
 
-		bool TrySuckPickupIn(cPickup & a_Pickup)
+		bool TrySuckPickupIn(cPickup * a_Pickup)
 		{
-			cItem & Item = a_Pickup.GetItem();
+			cItem & Item = a_Pickup->GetItem();
 
 			for (int i = 0; i < ContentsWidth * ContentsHeight; i++)
 			{
@@ -235,7 +238,7 @@ bool cHopperEntity::MovePickupsIn(cChunk & a_Chunk, Int64 a_CurrentTick)
 				{
 					m_bFoundPickupsAbove = true;
 					m_Contents.SetSlot(i, Item);
-					a_Pickup.Destroy();  // Kill pickup
+					a_Pickup->Destroy();  // Kill pickup
 
 					return true;
 				}
@@ -249,7 +252,7 @@ bool cHopperEntity::MovePickupsIn(cChunk & a_Chunk, Int64 a_CurrentTick)
 
 					if (Item.IsEmpty())
 					{
-						a_Pickup.Destroy();  // Kill pickup if all items were added
+						a_Pickup->Destroy();  // Kill pickup if all items were added
 					}
 					return true;
 				}
diff --git a/src/BlockEntities/MobSpawnerEntity.cpp b/src/BlockEntities/MobSpawnerEntity.cpp
index 8a4cc4d38..5246ae6ca 100644
--- a/src/BlockEntities/MobSpawnerEntity.cpp
+++ b/src/BlockEntities/MobSpawnerEntity.cpp
@@ -1,4 +1,4 @@
-
+
 #include "Globals.h"  // NOTE: MSVC stupidness requires this to be the same across all modules
 
 #include "MobSpawnerEntity.h"
@@ -138,36 +138,47 @@ void cMobSpawnerEntity::SpawnEntity(void)
 		return;
 	}
 
-	auto MobType = m_Entity;
-	bool EntitiesSpawned = m_World->DoWithChunk(GetChunkX(), GetChunkZ(), [&](cChunk & a_Chunk)
+	class cCallback : public cChunkCallback
+	{
+	public:
+		cCallback(int a_RelX, int a_RelY, int a_RelZ, eMonsterType a_MobType, int a_NearbyEntitiesNum) :
+			m_RelX(a_RelX),
+			m_RelY(a_RelY),
+			m_RelZ(a_RelZ),
+			m_MobType(a_MobType),
+			m_NearbyEntitiesNum(a_NearbyEntitiesNum)
+		{
+		}
+
+		virtual bool Item(cChunk * a_Chunk)
 		{
 			auto & Random = GetRandomProvider();
 
-			bool HaveSpawnedEntity = false;
+			bool EntitiesSpawned = false;
 			for (size_t i = 0; i < 4; i++)
 			{
-				if (NearbyEntities >= 6)
+				if (m_NearbyEntitiesNum >= 6)
 				{
 					break;
 				}
 
 				int RelX = m_RelX + static_cast<int>((Random.RandReal<double>() - Random.RandReal<double>()) * 4.0);
-				int RelY = m_PosY + Random.RandInt(-1, 1);
+				int RelY = m_RelY + Random.RandInt(-1, 1);
 				int RelZ = m_RelZ + static_cast<int>((Random.RandReal<double>() - Random.RandReal<double>()) * 4.0);
 
-				cChunk * Chunk = a_Chunk.GetRelNeighborChunkAdjustCoords(RelX, RelZ);
+				cChunk * Chunk = a_Chunk->GetRelNeighborChunkAdjustCoords(RelX, RelZ);
 				if ((Chunk == nullptr) || !Chunk->IsValid())
 				{
 					continue;
 				}
 				EMCSBiome Biome = Chunk->GetBiomeAt(RelX, RelZ);
 
-				if (cMobSpawner::CanSpawnHere(Chunk, RelX, RelY, RelZ, MobType, Biome))
+				if (cMobSpawner::CanSpawnHere(Chunk, RelX, RelY, RelZ, m_MobType, Biome))
 				{
 					double PosX = Chunk->GetPosX() * cChunkDef::Width + RelX;
 					double PosZ = Chunk->GetPosZ() * cChunkDef::Width + RelZ;
 
-					auto Monster = cMonster::NewMonsterFromType(MobType);
+					auto Monster = cMonster::NewMonsterFromType(m_MobType);
 					if (Monster == nullptr)
 					{
 						continue;
@@ -177,7 +188,7 @@ void cMobSpawnerEntity::SpawnEntity(void)
 					Monster->SetYaw(Random.RandReal(360.0f));
 					if (Chunk->GetWorld()->SpawnMobFinalize(std::move(Monster)) != cEntity::INVALID_ID)
 					{
-						HaveSpawnedEntity = true;
+						EntitiesSpawned = true;
 						Chunk->BroadcastSoundParticleEffect(
 							EffectID::PARTICLE_MOBSPAWN,
 							static_cast<int>(PosX * 8.0),
@@ -185,15 +196,19 @@ void cMobSpawnerEntity::SpawnEntity(void)
 							static_cast<int>(PosZ * 8.0),
 							0
 						);
-						NearbyEntities++;
+						m_NearbyEntitiesNum++;
 					}
 				}
 			}
 			return EntitiesSpawned;
 		}
-	);
+	protected:
+		int m_RelX, m_RelY, m_RelZ;
+		eMonsterType m_MobType;
+		int m_NearbyEntitiesNum;
+	} Callback(m_RelX, m_PosY, m_RelZ, m_Entity, NearbyEntities);
 
-	if (EntitiesSpawned)
+	if (m_World->DoWithChunk(GetChunkX(), GetChunkZ(), Callback))
 	{
 		ResetTimer();
 	}
diff --git a/src/Blocks/BlockBed.cpp b/src/Blocks/BlockBed.cpp
index 0032ec079..77572a254 100644
--- a/src/Blocks/BlockBed.cpp
+++ b/src/Blocks/BlockBed.cpp
@@ -1,12 +1,12 @@
-
+
 // BlockBed.cpp
 
 #include "Globals.h"
 #include "BlockBed.h"
 
 #include "BroadcastInterface.h"
+#include "Entities/../World.h"
 #include "Entities/Player.h"
-#include "../World.h"
 #include "../BoundingBox.h"
 #include "../Mobs/Monster.h"
 #include "../BlockEntities/BedEntity.h"
@@ -53,6 +53,66 @@ void cBlockBedHandler::OnDestroyed(cChunkInterface & a_ChunkInterface, cWorldInt
 
 
 
+class cFindMobs :
+	public cEntityCallback
+{
+	virtual bool Item(cEntity * a_Entity) override
+	{
+		return (
+			(a_Entity->GetEntityType() == cEntity::etMonster) &&
+			(static_cast<cMonster*>(a_Entity)->GetMobFamily() == cMonster::mfHostile)
+		);
+	}
+};
+
+
+
+
+
+class cTimeFastForwardTester :
+	public cPlayerListCallback
+{
+	virtual bool Item(cPlayer * a_Player) override
+	{
+		if (!a_Player->IsInBed())
+		{
+			return true;
+		}
+
+		return false;
+	}
+};
+
+
+
+
+
+class cPlayerBedStateUnsetter :
+	public cPlayerListCallback
+{
+public:
+	cPlayerBedStateUnsetter(Vector3i a_Position, cChunkInterface & a_ChunkInterface) :
+		m_Position(a_Position),
+		m_ChunkInterface(a_ChunkInterface)
+	{
+	}
+
+	virtual bool Item(cPlayer * a_Player) override
+	{
+		cBlockBedHandler::SetBedOccupationState(m_ChunkInterface, a_Player->GetLastBedPos(), false);
+		a_Player->SetIsInBed(false);
+		return false;
+	}
+
+private:
+	Vector3i m_Position;
+	cChunkInterface & m_ChunkInterface;
+};
+
+
+
+
+
 bool cBlockBedHandler::OnUse(cChunkInterface & a_ChunkInterface, cWorldInterface & a_WorldInterface, cPlayer & a_Player, int a_BlockX, int a_BlockY, int a_BlockZ, eBlockFace a_BlockFace, int a_CursorX, int a_CursorY, int a_CursorZ)
 {
 	if (a_WorldInterface.GetDimension() != dimOverworld)
@@ -73,14 +133,7 @@ bool cBlockBedHandler::OnUse(cChunkInterface & a_ChunkInterface, cWorldInterface
 		}
 		else
 		{
-			auto FindMobs = [](cEntity & a_Entity)
-			{
-				return (
-					(a_Entity.GetEntityType() == cEntity::etMonster) &&
-					(static_cast<cMonster&>(a_Entity).GetMobFamily() == cMonster::mfHostile)
-				);
-			};
-
+			cFindMobs FindMobs;
 			if (!a_Player.GetWorld()->ForEachEntityInBox(cBoundingBox(a_Player.GetPosition() - Vector3i(0, 5, 0), 8, 10), FindMobs))
 			{
 				a_Player.SendMessageFailure("You may not rest now, there are monsters nearby");
@@ -111,24 +164,11 @@ bool cBlockBedHandler::OnUse(cChunkInterface & a_ChunkInterface, cWorldInterface
 				a_Player.SetIsInBed(true);
 				a_Player.SendMessageSuccess("Home position set successfully");
 
-				auto TimeFastForwardTester = [](cPlayer & a_OtherPlayer)
+				cTimeFastForwardTester Tester;
+				if (a_WorldInterface.ForEachPlayer(Tester))
 				{
-					if (!a_OtherPlayer.IsInBed())
-					{
-						return true;
-					}
-					return false;
-				};
-
-				if (a_WorldInterface.ForEachPlayer(TimeFastForwardTester))
-				{
-					a_WorldInterface.ForEachPlayer([&](cPlayer & a_OtherPlayer)
-						{
-							cBlockBedHandler::SetBedOccupationState(a_ChunkInterface, a_OtherPlayer.GetLastBedPos(), false);
-							a_OtherPlayer.SetIsInBed(false);
-							return false;
-						}
-					);
+					cPlayerBedStateUnsetter Unsetter(Vector3i(a_BlockX + PillowDirection.x, a_BlockY, a_BlockZ + PillowDirection.z), a_ChunkInterface);
+					a_WorldInterface.ForEachPlayer(Unsetter);
 					a_WorldInterface.SetTimeOfDay(0);
 					a_ChunkInterface.SetBlockMeta(a_BlockX, a_BlockY, a_BlockZ, Meta & 0x0b);  // Clear the "occupied" bit of the bed's block
 				}
@@ -144,12 +184,25 @@ bool cBlockBedHandler::OnUse(cChunkInterface & a_ChunkInterface, cWorldInterface
 
 void cBlockBedHandler::OnPlacedByPlayer(cChunkInterface & a_ChunkInterface, cWorldInterface & a_WorldInterface, cPlayer & a_Player, const sSetBlock & a_BlockChange)
 {
-	a_Player.GetWorld()->DoWithBedAt(a_BlockChange.GetX(), a_BlockChange.GetY(), a_BlockChange.GetZ(), [&](cBedEntity & a_Bed)
+	class cBedColor :
+		public cBedCallback
+	{
+	public:
+		short m_Color;
+
+		cBedColor(short a_Color) :
+			m_Color(a_Color)
 		{
-			a_Bed.SetColor(a_Player.GetEquippedItem().m_ItemDamage);
+		}
+
+		virtual bool Item(cBedEntity * a_Bed) override
+		{
+			a_Bed->SetColor(m_Color);
 			return true;
 		}
-	);
+	};
+	cBedColor BedCallback(a_Player.GetEquippedItem().m_ItemDamage);
+	a_Player.GetWorld()->DoWithBedAt(a_BlockChange.GetX(), a_BlockChange.GetY(), a_BlockChange.GetZ(), BedCallback);
 }
 
 
@@ -158,12 +211,19 @@ void cBlockBedHandler::OnPlacedByPlayer(cChunkInterface & a_ChunkInterface, cWor
 
 void cBlockBedHandler::ConvertToPickups(cWorldInterface & a_WorldInterface, cItems & a_Pickups, NIBBLETYPE a_BlockMeta, int a_BlockX, int a_BlockY, int a_BlockZ)
 {
-	short Color = E_META_WOOL_RED;
-	a_WorldInterface.DoWithBedAt(a_BlockX, a_BlockY, a_BlockZ, [&](cBedEntity & a_Bed)
+	class cBedColor :
+		public cBedCallback
+	{
+	public:
+		short m_Color = E_META_WOOL_RED;
+
+		virtual bool Item(cBedEntity * a_Bed) override
 		{
-			Color = a_Bed.GetColor();
+			m_Color = a_Bed->GetColor();
 			return true;
 		}
-	);
-	a_Pickups.Add(cItem(E_ITEM_BED, 1, Color));
+	};
+	cBedColor BedCallback;
+	a_WorldInterface.DoWithBedAt(a_BlockX, a_BlockY, a_BlockZ, BedCallback);
+	a_Pickups.Add(cItem(E_ITEM_BED, 1, BedCallback.m_Color));
 }
diff --git a/src/Blocks/BlockMobHead.h b/src/Blocks/BlockMobHead.h
index 764cd7f65..30aba2491 100644
--- a/src/Blocks/BlockMobHead.h
+++ b/src/Blocks/BlockMobHead.h
@@ -30,32 +30,36 @@ public:
 			return;
 		}
 
-		a_WorldInterface.DoWithBlockEntityAt(a_BlockX, a_BlockY, a_BlockZ, [](cBlockEntity & a_BlockEntity)
+		class cCallback : public cBlockEntityCallback
+		{
+			virtual bool Item(cBlockEntity * a_BlockEntity)
 			{
-				if (a_BlockEntity.GetBlockType() != E_BLOCK_HEAD)
+				if (a_BlockEntity->GetBlockType() != E_BLOCK_HEAD)
 				{
 					return false;
 				}
-				auto & MobHeadEntity = static_cast<cMobHeadEntity&>(a_BlockEntity);
+				cMobHeadEntity * MobHeadEntity = static_cast<cMobHeadEntity*>(a_BlockEntity);
 
 				cItems Pickups;
-				Pickups.Add(E_ITEM_HEAD, 1, static_cast<short>(MobHeadEntity.GetType()));
+				Pickups.Add(E_ITEM_HEAD, 1, static_cast<short>(MobHeadEntity->GetType()));
 				auto & r1 = GetRandomProvider();
 
 				// Mid-block position first
 				double MicroX, MicroY, MicroZ;
-				MicroX = MobHeadEntity.GetPosX() + 0.5;
-				MicroY = MobHeadEntity.GetPosY() + 0.5;
-				MicroZ = MobHeadEntity.GetPosZ() + 0.5;
+				MicroX = MobHeadEntity->GetPosX() + 0.5;
+				MicroY = MobHeadEntity->GetPosY() + 0.5;
+				MicroZ = MobHeadEntity->GetPosZ() + 0.5;
 
 				// Add random offset second
 				MicroX += r1.RandReal<double>(-0.5, 0.5);
 				MicroZ += r1.RandReal<double>(-0.5, 0.5);
 
-				MobHeadEntity.GetWorld()->SpawnItemPickups(Pickups, MicroX, MicroY, MicroZ);
+				MobHeadEntity->GetWorld()->SpawnItemPickups(Pickups, MicroX, MicroY, MicroZ);
 				return false;
 			}
-		);
+		} Callback;
+
+		a_WorldInterface.DoWithBlockEntityAt(a_BlockX, a_BlockY, a_BlockZ, Callback);
 	}
 
 	virtual ColourID GetMapBaseColourID(NIBBLETYPE a_Meta) override
diff --git a/src/Blocks/WorldInterface.h b/src/Blocks/WorldInterface.h
index 4c1f6ddc8..524e8d642 100644
--- a/src/Blocks/WorldInterface.h
+++ b/src/Blocks/WorldInterface.h
@@ -1,18 +1,15 @@
-
+
 #pragma once
 
-#include <functional>
+
 #include "../Mobs/MonsterTypes.h"
 
-class cBedEntity;
-class cBlockEntity;
+
+typedef cItemCallback<cBlockEntity> cBlockEntityCallback;
 class cBroadcastInterface;
 class cItems;
 class cPlayer;
 
-using cBedCallback         = std::function<bool(cBedEntity   &)>;
-using cBlockEntityCallback = std::function<bool(cBlockEntity &)>;
-using cPlayerListCallback  = std::function<bool(cPlayer      &)>;
 
 
 
@@ -31,10 +28,7 @@ public:
 
 	virtual void DoExplosionAt(double a_ExplosionSize, double a_BlockX, double a_BlockY, double a_BlockZ, bool a_CanCauseFire, eExplosionSource a_Source, void * a_SourceData) = 0;
 
-	virtual bool DoWithBedAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBedCallback & a_Callback) = 0;
-
-	/** Calls the callback for the block entity at the specified coords; returns false if there's no block entity at those coords, true if found */
-	virtual bool DoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBlockEntityCallback & a_Callback) = 0;
+	virtual bool DoWithBedAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBedCallback & a_Callback) = 0;
 
 	/** Spawns item pickups for each item in the list. May compress pickups if too many entities: */
 	virtual void SpawnItemPickups(const cItems & a_Pickups, double a_BlockX, double a_BlockY, double a_BlockZ, double a_FlyAwaySpeed = 1.0, bool IsPlayerCreated = false) = 0;
@@ -52,16 +46,19 @@ public:
 	Returns the UniqueID of the spawned experience orb, or cEntity::INVALID_ID on failure. */
 	virtual UInt32 SpawnExperienceOrb(double a_X, double a_Y, double a_Z, int a_Reward) = 0;
 
+	/** Calls the callback for the block entity at the specified coords; returns false if there's no block entity at those coords, true if found */
+	virtual bool DoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBlockEntityCallback & a_Callback) = 0;
+
 	/** Sends the block on those coords to the player */
 	virtual void SendBlockTo(int a_BlockX, int a_BlockY, int a_BlockZ, cPlayer & a_Player) = 0;
 
 	/** Calls the callback for each player in the list; returns true if all players processed, false if the callback aborted by returning true */
-	virtual bool ForEachPlayer(const cPlayerListCallback & a_Callback) = 0;
+	virtual bool ForEachPlayer(cItemCallback<cPlayer> & a_Callback) = 0;
 
 	/** Calls the callback for each entity that has a nonempty intersection with the specified boundingbox.
 	Returns true if all entities processed, false if the callback aborted by returning true.
 	If any chunk in the box is missing, ignores the entities in that chunk silently. */
-	virtual bool ForEachEntityInBox(const cBoundingBox & a_Box, const cEntityCallback & a_Callback) = 0;
+	virtual bool ForEachEntityInBox(const cBoundingBox & a_Box, cEntityCallback & a_Callback) = 0;
 
 	virtual void SetTimeOfDay(int a_TimeOfDay) = 0;
 
diff --git a/src/Chunk.cpp b/src/Chunk.cpp
index 3a81b9ed1..78a8461d3 100644
--- a/src/Chunk.cpp
+++ b/src/Chunk.cpp
@@ -1,4 +1,4 @@
-
+
 #include "Globals.h"  // NOTE: MSVC stupidness requires this to be the same across all modules
 
 #ifndef _WIN32
@@ -2114,12 +2114,17 @@ bool cChunk::HasEntity(UInt32 a_EntityID)
 
 
 
-bool cChunk::ForEachEntity(const cEntityCallback & a_Callback)
+bool cChunk::ForEachEntity(cEntityCallback & a_Callback)
 {
 	// The entity list is locked by the parent chunkmap's CS
-	for (const auto & Entity : m_Entities)
+	for (auto itr = m_Entities.begin(), itr2 = itr; itr != m_Entities.end(); itr = itr2)
 	{
-		if (Entity->IsTicking() && a_Callback(*Entity))
+		++itr2;
+		if (!(*itr)->IsTicking())
+		{
+			continue;
+		}
+		if (a_Callback.Item(itr->get()))
 		{
 			return false;
 		}
@@ -2131,22 +2136,23 @@ bool cChunk::ForEachEntity(const cEntityCallback & a_Callback)
 
 
 
-bool cChunk::ForEachEntityInBox(const cBoundingBox & a_Box, const cEntityCallback & a_Callback)
+bool cChunk::ForEachEntityInBox(const cBoundingBox & a_Box, cEntityCallback & a_Callback)
 {
 	// The entity list is locked by the parent chunkmap's CS
-	for (const auto & Entity : m_Entities)
+	for (auto itr = m_Entities.begin(), itr2 = itr; itr != m_Entities.end(); itr = itr2)
 	{
-		if (!Entity->IsTicking())
+		++itr2;
+		if (!(*itr)->IsTicking())
 		{
 			continue;
 		}
-		cBoundingBox EntBox(Entity->GetPosition(), Entity->GetWidth() / 2, Entity->GetHeight());
+		cBoundingBox EntBox((*itr)->GetPosition(), (*itr)->GetWidth() / 2, (*itr)->GetHeight());
 		if (!EntBox.DoesIntersect(a_Box))
 		{
 			// The entity is not in the specified box
 			continue;
 		}
-		if (a_Callback(*Entity))
+		if (a_Callback.Item(itr->get()))
 		{
 			return false;
 		}
@@ -2158,14 +2164,23 @@ bool cChunk::ForEachEntityInBox(const cBoundingBox & a_Box, const cEntityCallbac
 
 
 
-bool cChunk::DoWithEntityByID(UInt32 a_EntityID, const cEntityCallback & a_Callback, bool & a_CallbackResult)
+bool cChunk::DoWithEntityByID(UInt32 a_EntityID, cEntityCallback & a_Callback, bool & a_CallbackResult)
+{
+	return DoWithEntityByID(a_EntityID, std::bind(&cEntityCallback::Item, &a_Callback, std::placeholders::_1), a_CallbackResult);
+}
+
+
+
+
+
+bool cChunk::DoWithEntityByID(UInt32 a_EntityID, cLambdaEntityCallback a_Callback, bool & a_CallbackResult)
 {
 	// The entity list is locked by the parent chunkmap's CS
 	for (const auto & Entity : m_Entities)
 	{
 		if ((Entity->GetUniqueID() == a_EntityID) && (Entity->IsTicking()))
 		{
-			a_CallbackResult = a_Callback(*Entity);
+			a_CallbackResult = a_Callback(Entity.get());
 			return true;
 		}
 	}  // for itr - m_Entitites[]
@@ -2177,7 +2192,7 @@ bool cChunk::DoWithEntityByID(UInt32 a_EntityID, const cEntityCallback & a_Callb
 
 
 template <class tyEntity, BLOCKTYPE... tBlocktype>
-bool cChunk::GenericForEachBlockEntity(const std::function<bool(tyEntity &)> & a_Callback)
+bool cChunk::GenericForEachBlockEntity(cItemCallback<tyEntity>& a_Callback)
 {
 	// The blockentity list is locked by the parent chunkmap's CS
 	for (auto & KeyPair : m_BlockEntities)
@@ -2188,7 +2203,7 @@ bool cChunk::GenericForEachBlockEntity(const std::function<bool(tyEntity &)> & a
 			(IsOneOf<tBlocktype...>(Block->GetBlockType()))
 		)
 		{
-			if (a_Callback(*static_cast<tyEntity *>(Block)))
+			if (a_Callback.Item(static_cast<tyEntity *>(Block)))
 			{
 				return false;
 			}
@@ -2201,7 +2216,7 @@ bool cChunk::GenericForEachBlockEntity(const std::function<bool(tyEntity &)> & a
 
 
 
-bool cChunk::ForEachBlockEntity(const cBlockEntityCallback & a_Callback)
+bool cChunk::ForEachBlockEntity(cBlockEntityCallback & a_Callback)
 {
 	return GenericForEachBlockEntity<cBlockEntity>(a_Callback);
 }
@@ -2210,7 +2225,7 @@ bool cChunk::ForEachBlockEntity(const cBlockEntityCallback & a_Callback)
 
 
 
-bool cChunk::ForEachBrewingstand(const cBrewingstandCallback & a_Callback)
+bool cChunk::ForEachBrewingstand(cBrewingstandCallback & a_Callback)
 {
 	return GenericForEachBlockEntity<cBrewingstandEntity,
 		E_BLOCK_BREWING_STAND
@@ -2221,7 +2236,7 @@ bool cChunk::ForEachBrewingstand(const cBrewingstandCallback & a_Callback)
 
 
 
-bool cChunk::ForEachChest(const cChestCallback & a_Callback)
+bool cChunk::ForEachChest(cChestCallback & a_Callback)
 {
 	return GenericForEachBlockEntity<cChestEntity,
 		E_BLOCK_CHEST
@@ -2232,7 +2247,7 @@ bool cChunk::ForEachChest(const cChestCallback & a_Callback)
 
 
 
-bool cChunk::ForEachDispenser(const cDispenserCallback & a_Callback)
+bool cChunk::ForEachDispenser(cDispenserCallback & a_Callback)
 {
 	return GenericForEachBlockEntity<cDispenserEntity,
 		E_BLOCK_DISPENSER
@@ -2243,7 +2258,7 @@ bool cChunk::ForEachDispenser(const cDispenserCallback & a_Callback)
 
 
 
-bool cChunk::ForEachDropper(const cDropperCallback & a_Callback)
+bool cChunk::ForEachDropper(cDropperCallback & a_Callback)
 {
 	return GenericForEachBlockEntity<cDropperEntity,
 		E_BLOCK_DROPPER
@@ -2254,7 +2269,7 @@ bool cChunk::ForEachDropper(const cDropperCallback & a_Callback)
 
 
 
-bool cChunk::ForEachDropSpenser(const cDropSpenserCallback & a_Callback)
+bool cChunk::ForEachDropSpenser(cDropSpenserCallback & a_Callback)
 {
 	return GenericForEachBlockEntity<cDropSpenserEntity,
 		E_BLOCK_DISPENSER,
@@ -2266,7 +2281,7 @@ bool cChunk::ForEachDropSpenser(const cDropSpenserCallback & a_Callback)
 
 
 
-bool cChunk::ForEachFurnace(const cFurnaceCallback & a_Callback)
+bool cChunk::ForEachFurnace(cFurnaceCallback & a_Callback)
 {
 	return GenericForEachBlockEntity<cFurnaceEntity,
 		E_BLOCK_FURNACE,
@@ -2279,7 +2294,7 @@ bool cChunk::ForEachFurnace(const cFurnaceCallback & a_Callback)
 
 
 template <class tyEntity, BLOCKTYPE... tBlocktype>
-bool cChunk::GenericDoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, const std::function<bool(tyEntity &)> & a_Callback)
+bool cChunk::GenericDoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, cItemCallback<tyEntity>& a_Callback)
 {
 	// The blockentity list is locked by the parent chunkmap's CS
 	cBlockEntity * Block = GetBlockEntity(a_BlockX, a_BlockY, a_BlockZ);
@@ -2294,14 +2309,14 @@ bool cChunk::GenericDoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ
 	{
 		return false;  // Not any of the given tBlocktypes
 	}
-	return !a_Callback(*static_cast<tyEntity *>(Block));
+	return !a_Callback.Item(static_cast<tyEntity *>(Block));
 }
 
 
 
 
 
-bool cChunk::DoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBlockEntityCallback & a_Callback)
+bool cChunk::DoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBlockEntityCallback & a_Callback)
 {
 	return GenericDoWithBlockEntityAt<cBlockEntity>(a_BlockX, a_BlockY, a_BlockZ, a_Callback);
 }
@@ -2309,7 +2324,7 @@ bool cChunk::DoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, const
 
 
 
-bool cChunk::DoWithBeaconAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBeaconCallback & a_Callback)
+bool cChunk::DoWithBeaconAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBeaconCallback & a_Callback)
 {
 	return GenericDoWithBlockEntityAt<cBeaconEntity,
 		E_BLOCK_BEACON
@@ -2319,7 +2334,7 @@ bool cChunk::DoWithBeaconAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBea
 
 
 
-bool cChunk::DoWithBedAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBedCallback & a_Callback)
+bool cChunk::DoWithBedAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBedCallback & a_Callback)
 {
 	return GenericDoWithBlockEntityAt<cBedEntity,
 		E_BLOCK_BED
@@ -2329,7 +2344,7 @@ bool cChunk::DoWithBedAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBedCal
 
 
 
-bool cChunk::DoWithBrewingstandAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBrewingstandCallback & a_Callback)
+bool cChunk::DoWithBrewingstandAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBrewingstandCallback & a_Callback)
 {
 	return GenericDoWithBlockEntityAt<cBrewingstandEntity,
 		E_BLOCK_BREWING_STAND
@@ -2340,7 +2355,7 @@ bool cChunk::DoWithBrewingstandAt(int a_BlockX, int a_BlockY, int a_BlockZ, cons
 
 
 
-bool cChunk::DoWithChestAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cChestCallback & a_Callback)
+bool cChunk::DoWithChestAt(int a_BlockX, int a_BlockY, int a_BlockZ, cChestCallback & a_Callback)
 {
 	return GenericDoWithBlockEntityAt<cChestEntity,
 		E_BLOCK_CHEST,
@@ -2352,7 +2367,7 @@ bool cChunk::DoWithChestAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cChes
 
 
 
-bool cChunk::DoWithDispenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cDispenserCallback & a_Callback)
+bool cChunk::DoWithDispenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, cDispenserCallback & a_Callback)
 {
 	return GenericDoWithBlockEntityAt<cDispenserEntity,
 		E_BLOCK_DISPENSER
@@ -2363,7 +2378,7 @@ bool cChunk::DoWithDispenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, const c
 
 
 
-bool cChunk::DoWithDropperAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cDropperCallback & a_Callback)
+bool cChunk::DoWithDropperAt(int a_BlockX, int a_BlockY, int a_BlockZ, cDropperCallback & a_Callback)
 {
 	return GenericDoWithBlockEntityAt<cDropperEntity,
 		E_BLOCK_DROPPER
@@ -2374,7 +2389,7 @@ bool cChunk::DoWithDropperAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cDr
 
 
 
-bool cChunk::DoWithDropSpenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cDropSpenserCallback & a_Callback)
+bool cChunk::DoWithDropSpenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, cDropSpenserCallback & a_Callback)
 {
 	return GenericDoWithBlockEntityAt<cDropSpenserEntity,
 		E_BLOCK_DISPENSER,
@@ -2386,7 +2401,7 @@ bool cChunk::DoWithDropSpenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, const
 
 
 
-bool cChunk::DoWithFurnaceAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cFurnaceCallback & a_Callback)
+bool cChunk::DoWithFurnaceAt(int a_BlockX, int a_BlockY, int a_BlockZ, cFurnaceCallback & a_Callback)
 {
 	return GenericDoWithBlockEntityAt<cFurnaceEntity,
 		E_BLOCK_FURNACE,
@@ -2398,7 +2413,7 @@ bool cChunk::DoWithFurnaceAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cFu
 
 
 
-bool cChunk::DoWithNoteBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cNoteBlockCallback & a_Callback)
+bool cChunk::DoWithNoteBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, cNoteBlockCallback & a_Callback)
 {
 	return GenericDoWithBlockEntityAt<cNoteEntity,
 		E_BLOCK_NOTE_BLOCK
@@ -2409,7 +2424,7 @@ bool cChunk::DoWithNoteBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, const c
 
 
 
-bool cChunk::DoWithCommandBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cCommandBlockCallback & a_Callback)
+bool cChunk::DoWithCommandBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, cCommandBlockCallback & a_Callback)
 {
 	return GenericDoWithBlockEntityAt<cCommandBlockEntity,
 		E_BLOCK_COMMAND_BLOCK
@@ -2420,7 +2435,7 @@ bool cChunk::DoWithCommandBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, cons
 
 
 
-bool cChunk::DoWithMobHeadAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cMobHeadCallback & a_Callback)
+bool cChunk::DoWithMobHeadAt(int a_BlockX, int a_BlockY, int a_BlockZ, cMobHeadCallback & a_Callback)
 {
 	return GenericDoWithBlockEntityAt<cMobHeadEntity,
 		E_BLOCK_HEAD
@@ -2431,7 +2446,7 @@ bool cChunk::DoWithMobHeadAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cMo
 
 
 
-bool cChunk::DoWithFlowerPotAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cFlowerPotCallback & a_Callback)
+bool cChunk::DoWithFlowerPotAt(int a_BlockX, int a_BlockY, int a_BlockZ, cFlowerPotCallback & a_Callback)
 {
 	return GenericDoWithBlockEntityAt<cFlowerPotEntity,
 		E_BLOCK_FLOWER_POT
diff --git a/src/Chunk.h b/src/Chunk.h
index 2523f2e5c..c5e252114 100644
--- a/src/Chunk.h
+++ b/src/Chunk.h
@@ -1,4 +1,4 @@
-
+
 #pragma once
 
 #include "Entities/Entity.h"
@@ -37,7 +37,18 @@ class cMobCensus;
 class cMobSpawner;
 class cSetChunkData;
 
-typedef std::list<cClientHandle *>                cClientHandleList;
+typedef std::list<cClientHandle *>         cClientHandleList;
+typedef cItemCallback<cEntity>             cEntityCallback;
+typedef cItemCallback<cBeaconEntity>       cBeaconCallback;
+typedef cItemCallback<cBedEntity>          cBedCallback;
+typedef cItemCallback<cBrewingstandEntity> cBrewingstandCallback;
+typedef cItemCallback<cChestEntity>        cChestCallback;
+typedef cItemCallback<cDispenserEntity>    cDispenserCallback;
+typedef cItemCallback<cFurnaceEntity>      cFurnaceCallback;
+typedef cItemCallback<cNoteEntity>         cNoteBlockCallback;
+typedef cItemCallback<cCommandBlockEntity> cCommandBlockCallback;
+typedef cItemCallback<cMobHeadEntity>      cMobHeadCallback;
+typedef cItemCallback<cFlowerPotEntity>    cFlowerPotCallback;
 
 // A convenience macro for calling GetChunkAndRelByAbsolute.
 #define PREPARE_REL_AND_CHUNK(Position, OriginalChunk) cChunk * Chunk; Vector3i Rel; bool RelSuccess = (OriginalChunk).GetChunkAndRelByAbsolute(Position, &Chunk, Rel);
@@ -247,86 +258,87 @@ public:
 	bool HasEntity(UInt32 a_EntityID);
 
 	/** Calls the callback for each entity; returns true if all entities processed, false if the callback aborted by returning true */
-	bool ForEachEntity(const cEntityCallback & a_Callback);  // Lua-accessible
+	bool ForEachEntity(cEntityCallback & a_Callback);  // Lua-accessible
 
 	/** Calls the callback for each entity that has a nonempty intersection with the specified boundingbox.
 	Returns true if all entities processed, false if the callback aborted by returning true. */
-	bool ForEachEntityInBox(const cBoundingBox & a_Box, const cEntityCallback & a_Callback);  // Lua-accessible
+	bool ForEachEntityInBox(const cBoundingBox & a_Box, cEntityCallback & a_Callback);  // Lua-accessible
 
 	/** Calls the callback if the entity with the specified ID is found, with the entity object as the callback param. Returns true if entity found. */
-	bool DoWithEntityByID(UInt32 a_EntityID, const cEntityCallback & a_Callback, bool & a_CallbackResult);  // Lua-accessible
+	bool DoWithEntityByID(UInt32 a_EntityID, cEntityCallback & a_Callback, bool & a_CallbackResult);  // Lua-accessible
+	bool DoWithEntityByID(UInt32 a_EntityID, cLambdaEntityCallback a_Callback, bool & a_CallbackResult);  // Lambda version
 
 	/** Calls the callback for each tyEntity; returns true if all block entities processed, false if the callback aborted by returning true
 	tBlocktypes are all blocktypes convertible to tyEntity which are to be called. If no block type is given the callback is called for every block entity
 	Accessible only from within Chunk.cpp */
 	template <class tyEntity, BLOCKTYPE... tBlocktype>
-	bool GenericForEachBlockEntity(const std::function<bool(tyEntity &)> & a_Callback);
+	bool GenericForEachBlockEntity(cItemCallback<tyEntity>& a_Callback);
 
 	/** Calls the callback for each block entity; returns true if all block entities processed, false if the callback aborted by returning true */
-	bool ForEachBlockEntity(const cBlockEntityCallback & a_Callback);  // Lua-accessible
+	bool ForEachBlockEntity(cBlockEntityCallback & a_Callback);  // Lua-accessible
 
 	/** Calls the callback for each brewingstand; returns true if all brewingstands processed, false if the callback aborted by returning true */
-	bool ForEachBrewingstand(const cBrewingstandCallback & a_Callback);  // Lua-accessible
+	bool ForEachBrewingstand(cBrewingstandCallback & a_Callback);  // Lua-accessible
 
 	/** Calls the callback for each chest; returns true if all chests processed, false if the callback aborted by returning true */
-	bool ForEachChest(const cChestCallback & a_Callback);  // Lua-accessible
+	bool ForEachChest(cChestCallback & a_Callback);  // Lua-accessible
 
 	/** Calls the callback for each dispenser; returns true if all dispensers processed, false if the callback aborted by returning true */
-	bool ForEachDispenser(const cDispenserCallback & a_Callback);
+	bool ForEachDispenser(cDispenserCallback & a_Callback);
 
 	/** Calls the callback for each dropper; returns true if all droppers processed, false if the callback aborted by returning true */
-	bool ForEachDropper(const cDropperCallback & a_Callback);
+	bool ForEachDropper(cDropperCallback & a_Callback);
 
 	/** Calls the callback for each dropspenser; returns true if all dropspensers processed, false if the callback aborted by returning true */
-	bool ForEachDropSpenser(const cDropSpenserCallback & a_Callback);
+	bool ForEachDropSpenser(cDropSpenserCallback & a_Callback);
 
 	/** Calls the callback for each furnace; returns true if all furnaces processed, false if the callback aborted by returning true */
-	bool ForEachFurnace(const cFurnaceCallback & a_Callback);  // Lua-accessible
+	bool ForEachFurnace(cFurnaceCallback & a_Callback);  // Lua-accessible
 
 	/** Calls the callback for the tyEntity at the specified coords; returns false if there's no such block entity at those coords, true if found
 	tBlocktype is a list of the blocktypes to be called. If no BLOCKTYPE template arguments are given the callback is called for any block entity
 	Accessible only from within Chunk.cpp */
 	template <class tyEntity, BLOCKTYPE... tBlocktype>
-	bool GenericDoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, const std::function<bool(tyEntity &)> & a_Callback);
+	bool GenericDoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, cItemCallback<tyEntity>& a_Callback);
 
 	/** Calls the callback for the block entity at the specified coords; returns false if there's no block entity at those coords, true if found */
-	bool DoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBlockEntityCallback & a_Callback);  // Lua-acessible
+	bool DoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBlockEntityCallback & a_Callback);  // Lua-acessible
 
 	/** Calls the callback for the beacon at the specified coords; returns false if there's no beacon at those coords, true if found */
-	bool DoWithBeaconAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBeaconCallback & a_Callback);  // Lua-acessible
+	bool DoWithBeaconAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBeaconCallback & a_Callback);  // Lua-acessible
 
 	/** Calls the callback for the brewingstand at the specified coords; returns false if there's no brewingstand at those coords, true if found */
-	bool DoWithBrewingstandAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBrewingstandCallback & a_Callback);  // Lua-acessible
+	bool DoWithBrewingstandAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBrewingstandCallback & a_Callback);  // Lua-acessible
 
 	/** Calls the callback for the bed at the specified coords; returns false if there's no bed at those coords, true if found */
-	bool DoWithBedAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBedCallback & a_Callback);  // Lua-acessible
+	bool DoWithBedAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBedCallback & a_Callback);  // Lua-acessible
 
 	/** Calls the callback for the chest at the specified coords; returns false if there's no chest at those coords, true if found */
-	bool DoWithChestAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cChestCallback & a_Callback);  // Lua-acessible
+	bool DoWithChestAt(int a_BlockX, int a_BlockY, int a_BlockZ, cChestCallback & a_Callback);  // Lua-acessible
 
 	/** Calls the callback for the dispenser at the specified coords; returns false if there's no dispenser at those coords or callback returns true, returns true if found */
-	bool DoWithDispenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cDispenserCallback & a_Callback);
+	bool DoWithDispenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, cDispenserCallback & a_Callback);
 
 	/** Calls the callback for the dispenser at the specified coords; returns false if there's no dropper at those coords or callback returns true, returns true if found */
-	bool DoWithDropperAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cDropperCallback & a_Callback);
+	bool DoWithDropperAt(int a_BlockX, int a_BlockY, int a_BlockZ, cDropperCallback & a_Callback);
 
 	/** Calls the callback for the dispenser at the specified coords; returns false if there's no dropspenser at those coords or callback returns true, returns true if found */
-	bool DoWithDropSpenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cDropSpenserCallback & a_Callback);
+	bool DoWithDropSpenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, cDropSpenserCallback & a_Callback);
 
 	/** Calls the callback for the furnace at the specified coords; returns false if there's no furnace at those coords or callback returns true, returns true if found */
-	bool DoWithFurnaceAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cFurnaceCallback & a_Callback);  // Lua-accessible
+	bool DoWithFurnaceAt(int a_BlockX, int a_BlockY, int a_BlockZ, cFurnaceCallback & a_Callback);  // Lua-accessible
 
 	/** Calls the callback for the noteblock at the specified coords; returns false if there's no noteblock at those coords or callback returns true, returns true if found */
-	bool DoWithNoteBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cNoteBlockCallback & a_Callback);
+	bool DoWithNoteBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, cNoteBlockCallback & a_Callback);
 
 	/** Calls the callback for the command block at the specified coords; returns false if there's no command block at those coords or callback returns true, returns true if found */
-	bool DoWithCommandBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cCommandBlockCallback & a_Callback);
+	bool DoWithCommandBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, cCommandBlockCallback & a_Callback);
 
 	/** Calls the callback for the mob head block at the specified coords; returns false if there's no mob head block at those coords or callback returns true, returns true if found */
-	bool DoWithMobHeadAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cMobHeadCallback & a_Callback);
+	bool DoWithMobHeadAt(int a_BlockX, int a_BlockY, int a_BlockZ, cMobHeadCallback & a_Callback);
 
 	/** Calls the callback for the flower pot at the specified coords; returns false if there's no flower pot at those coords or callback returns true, returns true if found */
-	bool DoWithFlowerPotAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cFlowerPotCallback & a_Callback);
+	bool DoWithFlowerPotAt(int a_BlockX, int a_BlockY, int a_BlockZ, cFlowerPotCallback & a_Callback);
 
 	/** Retrieves the test on the sign at the specified coords; returns false if there's no sign at those coords, true if found */
 	bool GetSignLines (int a_BlockX, int a_BlockY, int a_BlockZ, AString & a_Line1, AString & a_Line2, AString & a_Line3, AString & a_Line4);  // Lua-accessible
diff --git a/src/ChunkMap.cpp b/src/ChunkMap.cpp
index 524d5b2ff..6afce338d 100644
--- a/src/ChunkMap.cpp
+++ b/src/ChunkMap.cpp
@@ -1,4 +1,4 @@
-
+
 #include "Globals.h"  // NOTE: MSVC stupidness requires this to be the same across all modules
 
 #include "ChunkMap.h"
@@ -731,7 +731,7 @@ bool cChunkMap::UseBlockEntity(cPlayer * a_Player, int a_BlockX, int a_BlockY, i
 
 
 
-bool cChunkMap::DoWithChunk(int a_ChunkX, int a_ChunkZ, const cChunkCallback & a_Callback)
+bool cChunkMap::DoWithChunk(int a_ChunkX, int a_ChunkZ, cChunkCallback & a_Callback)
 {
 	cCSLock Lock(m_CSChunks);
 	cChunkPtr Chunk = GetChunkNoLoad(a_ChunkX, a_ChunkZ);
@@ -739,15 +739,30 @@ bool cChunkMap::DoWithChunk(int a_ChunkX, int a_ChunkZ, const cChunkCallback & a
 	{
 		return false;
 	}
-	return a_Callback(*Chunk);
+	return a_Callback.Item(Chunk);
 }
 
 
-bool cChunkMap::DoWithChunkAt(Vector3i a_BlockPos, const cChunkCallback & a_Callback)
+bool cChunkMap::DoWithChunkAt(Vector3i a_BlockPos, std::function<bool(cChunk &)> a_Callback)
 {
 	int ChunkX, ChunkZ;
 	cChunkDef::BlockToChunk(a_BlockPos.x, a_BlockPos.z, ChunkX, ChunkZ);
-	return DoWithChunk(ChunkX, ChunkZ, a_Callback);
+	struct cCallBackWrapper : cChunkCallback
+	{
+		cCallBackWrapper(std::function<bool(cChunk &)> a_InnerCallback) :
+			m_Callback(a_InnerCallback)
+		{
+		}
+
+		virtual bool Item(cChunk * a_Chunk)
+		{
+			return m_Callback(*a_Chunk);
+		}
+
+	private:
+		std::function<bool(cChunk &)> m_Callback;
+	} callback(a_Callback);
+	return DoWithChunk(ChunkX, ChunkZ, callback);
 }
 
 
@@ -1583,7 +1598,7 @@ OwnedEntity cChunkMap::RemoveEntity(cEntity & a_Entity)
 
 
 
-bool cChunkMap::ForEachEntity(const cEntityCallback & a_Callback)
+bool cChunkMap::ForEachEntity(cEntityCallback & a_Callback)
 {
 	cCSLock Lock(m_CSChunks);
 	for (const auto & Chunk : m_Chunks)
@@ -1600,7 +1615,7 @@ bool cChunkMap::ForEachEntity(const cEntityCallback & a_Callback)
 
 
 
-bool cChunkMap::ForEachEntityInChunk(int a_ChunkX, int a_ChunkZ, const cEntityCallback & a_Callback)
+bool cChunkMap::ForEachEntityInChunk(int a_ChunkX, int a_ChunkZ, cEntityCallback & a_Callback)
 {
 	cCSLock Lock(m_CSChunks);
 	cChunkPtr Chunk = GetChunkNoGen(a_ChunkX, a_ChunkZ);
@@ -1615,7 +1630,7 @@ bool cChunkMap::ForEachEntityInChunk(int a_ChunkX, int a_ChunkZ, const cEntityCa
 
 
 
-bool cChunkMap::ForEachEntityInBox(const cBoundingBox & a_Box, const cEntityCallback & a_Callback)
+bool cChunkMap::ForEachEntityInBox(const cBoundingBox & a_Box, cEntityCallback & a_Callback)
 {
 	// Calculate the chunk range for the box:
 	int MinChunkX = FloorC(a_Box.GetMinX() / cChunkDef::Width);
@@ -1777,41 +1792,60 @@ void cChunkMap::DoExplosionAt(double a_ExplosionSize, double a_BlockX, double a_
 		area.Write(*m_World, bx - ExplosionSizeInt, MinY, bz - ExplosionSizeInt);
 	}
 
-	Vector3d ExplosionPos{ a_BlockX, a_BlockY, a_BlockZ };
-	cBoundingBox bbTNT(ExplosionPos, 0.5, 1);
-	bbTNT.Expand(ExplosionSizeInt * 2, ExplosionSizeInt * 2, ExplosionSizeInt * 2);
+	class cTNTDamageCallback :
+		public cEntityCallback
+	{
+	public:
+		cTNTDamageCallback(cBoundingBox & a_CBBBTNT, Vector3d a_CBExplosionPos, int a_CBExplosionSize) :
+			m_bbTNT(a_CBBBTNT),
+			m_ExplosionPos(a_CBExplosionPos),
+			m_ExplosionSize(a_CBExplosionSize)
+		{
+		}
 
-	ForEachEntity([&](cEntity & a_Entity)
+		virtual bool Item(cEntity * a_Entity) override
 		{
-			if (a_Entity.IsPickup() && (a_Entity.GetTicksAlive() < 20))
+			if (a_Entity->IsPickup() && (a_Entity->GetTicksAlive() < 20))
 			{
 				// If pickup age is smaller than one second, it is invincible (so we don't kill pickups that were just spawned)
 				return false;
 			}
 
-			Vector3d DistanceFromExplosion = a_Entity.GetPosition() - ExplosionPos;
+			Vector3d DistanceFromExplosion = a_Entity->GetPosition() - m_ExplosionPos;
 
-			if (!a_Entity.IsTNT() && !a_Entity.IsFallingBlock())  // Don't apply damage to other TNT entities and falling blocks, they should be invincible
+			if (!a_Entity->IsTNT() && !a_Entity->IsFallingBlock())  // Don't apply damage to other TNT entities and falling blocks, they should be invincible
 			{
-				cBoundingBox bbEntity(a_Entity.GetPosition(), a_Entity.GetWidth() / 2, a_Entity.GetHeight());
+				cBoundingBox bbEntity(a_Entity->GetPosition(), a_Entity->GetWidth() / 2, a_Entity->GetHeight());
 
-				if (!bbTNT.IsInside(bbEntity))  // If bbEntity is inside bbTNT, not vice versa!
+				if (!m_bbTNT.IsInside(bbEntity))  // If bbEntity is inside bbTNT, not vice versa!
 				{
 					return false;
 				}
 
 				// Ensure that the damage dealt is inversely proportional to the distance to the TNT centre - the closer a player is, the harder they are hit
-				a_Entity.TakeDamage(dtExplosion, nullptr, static_cast<int>((1 / DistanceFromExplosion.Length()) * 6 * ExplosionSizeInt), 0);
+				a_Entity->TakeDamage(dtExplosion, nullptr, static_cast<int>((1 / DistanceFromExplosion.Length()) * 6 * m_ExplosionSize), 0);
 			}
 
 			// Apply force to entities around the explosion - code modified from World.cpp DoExplosionAt()
 			DistanceFromExplosion.Normalize();
-			DistanceFromExplosion *= ExplosionSizeInt * ExplosionSizeInt;
-			a_Entity.AddSpeed(DistanceFromExplosion);
+			DistanceFromExplosion *= m_ExplosionSize * m_ExplosionSize;
+			a_Entity->AddSpeed(DistanceFromExplosion);
 
 			return false;
 		}
-	);
+
+	protected:
+		cBoundingBox & m_bbTNT;
+		Vector3d m_ExplosionPos;
+		int m_ExplosionSize;
+	};
+
+	cBoundingBox bbTNT(Vector3d(a_BlockX, a_BlockY, a_BlockZ), 0.5, 1);
+	bbTNT.Expand(ExplosionSizeInt * 2, ExplosionSizeInt * 2, ExplosionSizeInt * 2);
+
+
+	cTNTDamageCallback TNTDamageCallback(bbTNT, Vector3d(a_BlockX, a_BlockY, a_BlockZ), ExplosionSizeInt);
+	ForEachEntity(TNTDamageCallback);
 
 	// Wake up all simulators for the area, so that water and lava flows and sand falls into the blasted holes (FS #391):
 	m_World->GetSimulatorManager()->WakeUpArea(cCuboid(
@@ -1824,7 +1858,16 @@ void cChunkMap::DoExplosionAt(double a_ExplosionSize, double a_BlockX, double a_
 
 
 
-bool cChunkMap::DoWithEntityByID(UInt32 a_UniqueID, const cEntityCallback & a_Callback)
+bool cChunkMap::DoWithEntityByID(UInt32 a_UniqueID, cEntityCallback & a_Callback)
+{
+	return DoWithEntityByID(a_UniqueID, std::bind(&cEntityCallback::Item, &a_Callback, std::placeholders::_1));
+}
+
+
+
+
+
+bool cChunkMap::DoWithEntityByID(UInt32 a_UniqueID, cLambdaEntityCallback a_Callback)
 {
 	cCSLock Lock(m_CSChunks);
 	bool res = false;
@@ -1842,7 +1885,7 @@ bool cChunkMap::DoWithEntityByID(UInt32 a_UniqueID, const cEntityCallback & a_Ca
 
 
 
-bool cChunkMap::ForEachBlockEntityInChunk(int a_ChunkX, int a_ChunkZ, const cBlockEntityCallback & a_Callback)
+bool cChunkMap::ForEachBlockEntityInChunk(int a_ChunkX, int a_ChunkZ, cBlockEntityCallback & a_Callback)
 {
 	cCSLock Lock(m_CSChunks);
 	cChunkPtr Chunk = GetChunkNoGen(a_ChunkX, a_ChunkZ);
@@ -1857,7 +1900,7 @@ bool cChunkMap::ForEachBlockEntityInChunk(int a_ChunkX, int a_ChunkZ, const cBlo
 
 
 
-bool cChunkMap::ForEachBrewingstandInChunk(int a_ChunkX, int a_ChunkZ, const cBrewingstandCallback & a_Callback)
+bool cChunkMap::ForEachBrewingstandInChunk(int a_ChunkX, int a_ChunkZ, cBrewingstandCallback & a_Callback)
 {
 	cCSLock Lock(m_CSChunks);
 	cChunkPtr Chunk = GetChunkNoGen(a_ChunkX, a_ChunkZ);
@@ -1872,7 +1915,7 @@ bool cChunkMap::ForEachBrewingstandInChunk(int a_ChunkX, int a_ChunkZ, const cBr
 
 
 
-bool cChunkMap::ForEachChestInChunk(int a_ChunkX, int a_ChunkZ, const cChestCallback & a_Callback)
+bool cChunkMap::ForEachChestInChunk(int a_ChunkX, int a_ChunkZ, cChestCallback & a_Callback)
 {
 	cCSLock Lock(m_CSChunks);
 	cChunkPtr Chunk = GetChunkNoGen(a_ChunkX, a_ChunkZ);
@@ -1887,7 +1930,7 @@ bool cChunkMap::ForEachChestInChunk(int a_ChunkX, int a_ChunkZ, const cChestCall
 
 
 
-bool cChunkMap::ForEachDispenserInChunk(int a_ChunkX, int a_ChunkZ, const cDispenserCallback & a_Callback)
+bool cChunkMap::ForEachDispenserInChunk(int a_ChunkX, int a_ChunkZ, cDispenserCallback & a_Callback)
 {
 	cCSLock Lock(m_CSChunks);
 	cChunkPtr Chunk = GetChunkNoGen(a_ChunkX, a_ChunkZ);
@@ -1902,7 +1945,7 @@ bool cChunkMap::ForEachDispenserInChunk(int a_ChunkX, int a_ChunkZ, const cDispe
 
 
 
-bool cChunkMap::ForEachDropperInChunk(int a_ChunkX, int a_ChunkZ, const cDropperCallback & a_Callback)
+bool cChunkMap::ForEachDropperInChunk(int a_ChunkX, int a_ChunkZ, cDropperCallback & a_Callback)
 {
 	cCSLock Lock(m_CSChunks);
 	cChunkPtr Chunk = GetChunkNoGen(a_ChunkX, a_ChunkZ);
@@ -1917,7 +1960,7 @@ bool cChunkMap::ForEachDropperInChunk(int a_ChunkX, int a_ChunkZ, const cDropper
 
 
 
-bool cChunkMap::ForEachDropSpenserInChunk(int a_ChunkX, int a_ChunkZ, const cDropSpenserCallback & a_Callback)
+bool cChunkMap::ForEachDropSpenserInChunk(int a_ChunkX, int a_ChunkZ, cDropSpenserCallback & a_Callback)
 {
 	cCSLock Lock(m_CSChunks);
 	cChunkPtr Chunk = GetChunkNoGen(a_ChunkX, a_ChunkZ);
@@ -1932,7 +1975,7 @@ bool cChunkMap::ForEachDropSpenserInChunk(int a_ChunkX, int a_ChunkZ, const cDro
 
 
 
-bool cChunkMap::ForEachFurnaceInChunk(int a_ChunkX, int a_ChunkZ, const cFurnaceCallback & a_Callback)
+bool cChunkMap::ForEachFurnaceInChunk(int a_ChunkX, int a_ChunkZ, cFurnaceCallback & a_Callback)
 {
 	cCSLock Lock(m_CSChunks);
 	cChunkPtr Chunk = GetChunkNoGen(a_ChunkX, a_ChunkZ);
@@ -1947,7 +1990,7 @@ bool cChunkMap::ForEachFurnaceInChunk(int a_ChunkX, int a_ChunkZ, const cFurnace
 
 
 
-bool cChunkMap::DoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBlockEntityCallback & a_Callback)
+bool cChunkMap::DoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBlockEntityCallback & a_Callback)
 {
 	int ChunkX, ChunkZ;
 	int BlockX = a_BlockX, BlockY = a_BlockY, BlockZ = a_BlockZ;
@@ -1965,7 +2008,7 @@ bool cChunkMap::DoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, co
 
 
 
-bool cChunkMap::DoWithBeaconAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBeaconCallback & a_Callback)
+bool cChunkMap::DoWithBeaconAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBeaconCallback & a_Callback)
 {
 	int ChunkX, ChunkZ;
 	int BlockX = a_BlockX, BlockY = a_BlockY, BlockZ = a_BlockZ;
@@ -1983,7 +2026,7 @@ bool cChunkMap::DoWithBeaconAt(int a_BlockX, int a_BlockY, int a_BlockZ, const c
 
 
 
-bool cChunkMap::DoWithBedAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBedCallback & a_Callback)
+bool cChunkMap::DoWithBedAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBedCallback & a_Callback)
 {
 	int ChunkX, ChunkZ;
 	int BlockX = a_BlockX, BlockY = a_BlockY, BlockZ = a_BlockZ;
@@ -2001,7 +2044,7 @@ bool cChunkMap::DoWithBedAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBed
 
 
 
-bool cChunkMap::DoWithBrewingstandAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBrewingstandCallback & a_Callback)
+bool cChunkMap::DoWithBrewingstandAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBrewingstandCallback & a_Callback)
 {
 	int ChunkX, ChunkZ;
 	int BlockX = a_BlockX, BlockY = a_BlockY, BlockZ = a_BlockZ;
@@ -2019,7 +2062,7 @@ bool cChunkMap::DoWithBrewingstandAt(int a_BlockX, int a_BlockY, int a_BlockZ, c
 
 
 
-bool cChunkMap::DoWithChestAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cChestCallback & a_Callback)
+bool cChunkMap::DoWithChestAt(int a_BlockX, int a_BlockY, int a_BlockZ, cChestCallback & a_Callback)
 {
 	int ChunkX, ChunkZ;
 	int BlockX = a_BlockX, BlockY = a_BlockY, BlockZ = a_BlockZ;
@@ -2037,7 +2080,7 @@ bool cChunkMap::DoWithChestAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cC
 
 
 
-bool cChunkMap::DoWithDispenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cDispenserCallback & a_Callback)
+bool cChunkMap::DoWithDispenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, cDispenserCallback & a_Callback)
 {
 	int ChunkX, ChunkZ;
 	int BlockX = a_BlockX, BlockY = a_BlockY, BlockZ = a_BlockZ;
@@ -2055,7 +2098,7 @@ bool cChunkMap::DoWithDispenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, cons
 
 
 
-bool cChunkMap::DoWithDropperAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cDropperCallback & a_Callback)
+bool cChunkMap::DoWithDropperAt(int a_BlockX, int a_BlockY, int a_BlockZ, cDropperCallback & a_Callback)
 {
 	int ChunkX, ChunkZ;
 	int BlockX = a_BlockX, BlockY = a_BlockY, BlockZ = a_BlockZ;
@@ -2073,7 +2116,7 @@ bool cChunkMap::DoWithDropperAt(int a_BlockX, int a_BlockY, int a_BlockZ, const
 
 
 
-bool cChunkMap::DoWithDropSpenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cDropSpenserCallback & a_Callback)
+bool cChunkMap::DoWithDropSpenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, cDropSpenserCallback & a_Callback)
 {
 	int ChunkX, ChunkZ;
 	int BlockX = a_BlockX, BlockY = a_BlockY, BlockZ = a_BlockZ;
@@ -2091,7 +2134,7 @@ bool cChunkMap::DoWithDropSpenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, co
 
 
 
-bool cChunkMap::DoWithFurnaceAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cFurnaceCallback & a_Callback)
+bool cChunkMap::DoWithFurnaceAt(int a_BlockX, int a_BlockY, int a_BlockZ, cFurnaceCallback & a_Callback)
 {
 	int ChunkX, ChunkZ;
 	int BlockX = a_BlockX, BlockY = a_BlockY, BlockZ = a_BlockZ;
@@ -2108,7 +2151,7 @@ bool cChunkMap::DoWithFurnaceAt(int a_BlockX, int a_BlockY, int a_BlockZ, const
 
 
 
-bool cChunkMap::DoWithNoteBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cNoteBlockCallback & a_Callback)
+bool cChunkMap::DoWithNoteBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, cNoteBlockCallback & a_Callback)
 {
 	int ChunkX, ChunkZ;
 	int BlockX = a_BlockX, BlockY = a_BlockY, BlockZ = a_BlockZ;
@@ -2125,7 +2168,7 @@ bool cChunkMap::DoWithNoteBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, cons
 
 
 
-bool cChunkMap::DoWithCommandBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cCommandBlockCallback & a_Callback)
+bool cChunkMap::DoWithCommandBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, cCommandBlockCallback & a_Callback)
 {
 	int ChunkX, ChunkZ;
 	int BlockX = a_BlockX, BlockY = a_BlockY, BlockZ = a_BlockZ;
@@ -2143,7 +2186,7 @@ bool cChunkMap::DoWithCommandBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, c
 
 
 
-bool cChunkMap::DoWithMobHeadAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cMobHeadCallback & a_Callback)
+bool cChunkMap::DoWithMobHeadAt(int a_BlockX, int a_BlockY, int a_BlockZ, cMobHeadCallback & a_Callback)
 {
 	int ChunkX, ChunkZ;
 	int BlockX = a_BlockX, BlockY = a_BlockY, BlockZ = a_BlockZ;
@@ -2161,7 +2204,7 @@ bool cChunkMap::DoWithMobHeadAt(int a_BlockX, int a_BlockY, int a_BlockZ, const
 
 
 
-bool cChunkMap::DoWithFlowerPotAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cFlowerPotCallback & a_Callback)
+bool cChunkMap::DoWithFlowerPotAt(int a_BlockX, int a_BlockY, int a_BlockZ, cFlowerPotCallback & a_Callback)
 {
 	int ChunkX, ChunkZ;
 	int BlockX = a_BlockX, BlockY = a_BlockY, BlockZ = a_BlockZ;
@@ -2399,7 +2442,7 @@ bool cChunkMap::ForEachChunkInRect(int a_MinChunkX, int a_MaxChunkX, int a_MinCh
 
 
 
-bool cChunkMap::ForEachLoadedChunk(const std::function<bool(int, int)> & a_Callback)
+bool cChunkMap::ForEachLoadedChunk(std::function<bool(int, int)> a_Callback)
 {
 	cCSLock Lock(m_CSChunks);
 	for (const auto & Chunk : m_Chunks)
diff --git a/src/ChunkMap.h b/src/ChunkMap.h
index 4f0ff47af..66d1d4840 100644
--- a/src/ChunkMap.h
+++ b/src/ChunkMap.h
@@ -1,4 +1,4 @@
-
+
 // cChunkMap.h
 
 // Interfaces to the cChunkMap class representing the chunk storage for a single world
@@ -38,23 +38,25 @@ class cSetChunkData;
 class cBoundingBox;
 class cDeadlockDetect;
 
-typedef std::list<cClientHandle *> cClientHandleList;
-typedef cChunk *                   cChunkPtr;
-using cEntityCallback       = std::function<bool(cEntity             &)>;
-using cBeaconCallback       = std::function<bool(cBeaconEntity       &)>;
-using cBedCallback          = std::function<bool(cBedEntity          &)>;
-using cBlockEntityCallback  = std::function<bool(cBlockEntity        &)>;
-using cBrewingstandCallback = std::function<bool(cBrewingstandEntity &)>;
-using cChestCallback        = std::function<bool(cChestEntity        &)>;
-using cChunkCallback        = std::function<bool(cChunk              &)>;
-using cDispenserCallback    = std::function<bool(cDispenserEntity    &)>;
-using cDropperCallback      = std::function<bool(cDropperEntity      &)>;
-using cDropSpenserCallback  = std::function<bool(cDropSpenserEntity  &)>;
-using cFurnaceCallback      = std::function<bool(cFurnaceEntity      &)>;
-using cNoteBlockCallback    = std::function<bool(cNoteEntity         &)>;
-using cCommandBlockCallback = std::function<bool(cCommandBlockEntity &)>;
-using cMobHeadCallback      = std::function<bool(cMobHeadEntity      &)>;
-using cFlowerPotCallback    = std::function<bool(cFlowerPotEntity    &)>;
+typedef std::list<cClientHandle *>         cClientHandleList;
+typedef cChunk *                           cChunkPtr;
+typedef cItemCallback<cEntity>             cEntityCallback;
+typedef cItemCallback<cBlockEntity>        cBlockEntityCallback;
+typedef cItemCallback<cBeaconEntity>       cBeaconCallback;
+typedef cItemCallback<cBedEntity>          cBedCallback;
+typedef cItemCallback<cBrewingstandEntity> cBrewingstandCallback;
+typedef cItemCallback<cChestEntity>        cChestCallback;
+typedef cItemCallback<cDispenserEntity>    cDispenserCallback;
+typedef cItemCallback<cDropperEntity>      cDropperCallback;
+typedef cItemCallback<cDropSpenserEntity>  cDropSpenserCallback;
+typedef cItemCallback<cFlowerPotEntity>    cFlowerPotCallback;
+typedef cItemCallback<cFurnaceEntity>      cFurnaceCallback;
+typedef cItemCallback<cNoteEntity>         cNoteBlockCallback;
+typedef cItemCallback<cCommandBlockEntity> cCommandBlockCallback;
+typedef cItemCallback<cMobHeadEntity>      cMobHeadCallback;
+typedef cItemCallback<cChunk>              cChunkCallback;
+
+typedef std::function<bool (cEntity *)>    cLambdaEntityCallback;
 
 
 
@@ -104,10 +106,10 @@ public:
 	bool UseBlockEntity(cPlayer * a_Player, int a_X, int a_Y, int a_Z);
 
 	/** Calls the callback for the chunk specified, with ChunkMapCS locked; returns false if the chunk doesn't exist, otherwise returns the same value as the callback */
-	bool DoWithChunk(int a_ChunkX, int a_ChunkZ, const cChunkCallback & a_Callback);
+	bool DoWithChunk(int a_ChunkX, int a_ChunkZ, cChunkCallback & a_Callback);
 
 	/** Calls the callback for the chunk at the block position specified, with ChunkMapCS locked; returns false if the chunk doesn't exist, otherwise returns the same value as the callback */
-	bool DoWithChunkAt(Vector3i a_BlockPos, const cChunkCallback & a_Callback);
+	bool DoWithChunkAt(Vector3i a_BlockPos, std::function<bool(cChunk &)> a_Callback);
 
 	/** Wakes up simulators for the specified block */
 	void WakeUpSimulators(Vector3i a_Block);
@@ -228,101 +230,102 @@ public:
 	OwnedEntity RemoveEntity(cEntity & a_Entity);
 
 	/** Calls the callback for each entity in the entire world; returns true if all entities processed, false if the callback aborted by returning true */
-	bool ForEachEntity(const cEntityCallback & a_Callback);  // Lua-accessible
+	bool ForEachEntity(cEntityCallback & a_Callback);  // Lua-accessible
 
 	/** Calls the callback for each entity in the specified chunk; returns true if all entities processed, false if the callback aborted by returning true */
-	bool ForEachEntityInChunk(int a_ChunkX, int a_ChunkZ, const cEntityCallback & a_Callback);  // Lua-accessible
+	bool ForEachEntityInChunk(int a_ChunkX, int a_ChunkZ, cEntityCallback & a_Callback);  // Lua-accessible
 
 	/** Calls the callback for each entity that has a nonempty intersection with the specified boundingbox.
 	Returns true if all entities processed, false if the callback aborted by returning true.
 	If any chunk in the box is missing, ignores the entities in that chunk silently. */
-	bool ForEachEntityInBox(const cBoundingBox & a_Box, const cEntityCallback & a_Callback);  // Lua-accessible
+	bool ForEachEntityInBox(const cBoundingBox & a_Box, cEntityCallback & a_Callback);  // Lua-accessible
 
 	/** Destroys and returns a list of blocks destroyed in the explosion at the specified coordinates */
 	void DoExplosionAt(double a_ExplosionSize, double a_BlockX, double a_BlockY, double a_BlockZ, cVector3iArray & a_BlockAffected);
 
 	/** Calls the callback if the entity with the specified ID is found, with the entity object as the callback param.
 	Returns true if entity found and callback returned false. */
-	bool DoWithEntityByID(UInt32 a_EntityID, const cEntityCallback & a_Callback);  // Lua-accessible
+	bool DoWithEntityByID(UInt32 a_EntityID, cEntityCallback & a_Callback);  // Lua-accessible
+	bool DoWithEntityByID(UInt32 a_EntityID, cLambdaEntityCallback a_Callback);  // Lambda version
 
 	/** Calls the callback for each block entity in the specified chunk.
 	Returns true if all block entities processed, false if the callback aborted by returning true. */
-	bool ForEachBlockEntityInChunk(int a_ChunkX, int a_ChunkZ, const cBlockEntityCallback & a_Callback);  // Lua-accessible
+	bool ForEachBlockEntityInChunk(int a_ChunkX, int a_ChunkZ, cBlockEntityCallback & a_Callback);  // Lua-accessible
 
 	/** Calls the callback for brewingstand in the specified chunk.
 	Returns true if all brewingstands processed, false if the callback aborted by returning true. */
-	bool ForEachBrewingstandInChunk(int a_ChunkX, int a_ChunkZ, const cBrewingstandCallback & a_Callback);  // Lua-accessible
+	bool ForEachBrewingstandInChunk(int a_ChunkX, int a_ChunkZ, cBrewingstandCallback & a_Callback);  // Lua-accessible
 
 	/** Calls the callback for each chest in the specified chunk.
 	Returns true if all chests processed, false if the callback aborted by returning true. */
-	bool ForEachChestInChunk(int a_ChunkX, int a_ChunkZ, const cChestCallback & a_Callback);  // Lua-accessible
+	bool ForEachChestInChunk(int a_ChunkX, int a_ChunkZ, cChestCallback & a_Callback);  // Lua-accessible
 
 	/** Calls the callback for each dispenser in the specified chunk.
 	Returns true if all dispensers processed, false if the callback aborted by returning true. */
-	bool ForEachDispenserInChunk(int a_ChunkX, int a_ChunkZ, const cDispenserCallback & a_Callback);
+	bool ForEachDispenserInChunk(int a_ChunkX, int a_ChunkZ, cDispenserCallback & a_Callback);
 
 	/** Calls the callback for each dropper in the specified chunk.
 	Returns true if all droppers processed, false if the callback aborted by returning true. */
-	bool ForEachDropperInChunk(int a_ChunkX, int a_ChunkZ, const cDropperCallback & a_Callback);
+	bool ForEachDropperInChunk(int a_ChunkX, int a_ChunkZ, cDropperCallback & a_Callback);
 
 	/** Calls the callback for each dropspenser in the specified chunk.
 	Returns true if all dropspensers processed, false if the callback aborted by returning true. */
-	bool ForEachDropSpenserInChunk(int a_ChunkX, int a_ChunkZ, const cDropSpenserCallback & a_Callback);
+	bool ForEachDropSpenserInChunk(int a_ChunkX, int a_ChunkZ, cDropSpenserCallback & a_Callback);
 
 	/** Calls the callback for each furnace in the specified chunk.
 	Returns true if all furnaces processed, false if the callback aborted by returning true. */
-	bool ForEachFurnaceInChunk(int a_ChunkX, int a_ChunkZ, const cFurnaceCallback & a_Callback);  // Lua-accessible
+	bool ForEachFurnaceInChunk(int a_ChunkX, int a_ChunkZ, cFurnaceCallback & a_Callback);  // Lua-accessible
 
 	/** Calls the callback for the block entity at the specified coords.
 	Returns false if there's no block entity at those coords, true if found. */
-	bool DoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBlockEntityCallback & a_Callback);  // Lua-acessible
+	bool DoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBlockEntityCallback & a_Callback);  // Lua-acessible
 
 	/** Calls the callback for the beacon at the specified coords.
 	Returns false if there's no beacon at those coords, true if found. */
-	bool DoWithBeaconAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBeaconCallback & a_Callback);  // Lua-acessible
+	bool DoWithBeaconAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBeaconCallback & a_Callback);  // Lua-acessible
 
 	/** Calls the callback for the bed at the specified coords.
 	Returns false if there's no bed at those coords, true if found. */
-	bool DoWithBedAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBedCallback & a_Callback);  // Lua-acessible
+	bool DoWithBedAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBedCallback & a_Callback);  // Lua-acessible
 
 	/** Calls the callback for the brewingstand at the specified coords; returns false if there's no brewingstand at those coords, true if found */
-	bool DoWithBrewingstandAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBrewingstandCallback & a_Callback);  // Lua-acessible
+	bool DoWithBrewingstandAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBrewingstandCallback & a_Callback);  // Lua-acessible
 
 	/** Calls the callback for the chest at the specified coords.
 	Returns false if there's no chest at those coords, true if found. */
-	bool DoWithChestAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cChestCallback & a_Callback);  // Lua-acessible
+	bool DoWithChestAt(int a_BlockX, int a_BlockY, int a_BlockZ, cChestCallback & a_Callback);  // Lua-acessible
 
 	/** Calls the callback for the dispenser at the specified coords.
 	Returns false if there's no dispenser at those coords or callback returns true, returns true if found. */
-	bool DoWithDispenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cDispenserCallback & a_Callback);  // Lua-accessible
+	bool DoWithDispenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, cDispenserCallback & a_Callback);  // Lua-accessible
 
 	/** Calls the callback for the dropper at the specified coords.
 	Returns false if there's no dropper at those coords or callback returns true, returns true if found. */
-	bool DoWithDropperAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cDropperCallback & a_Callback);  // Lua-accessible
+	bool DoWithDropperAt(int a_BlockX, int a_BlockY, int a_BlockZ, cDropperCallback & a_Callback);  // Lua-accessible
 
 	/** Calls the callback for the dropspenser at the specified coords.
 	Returns false if there's no dropspenser at those coords or callback returns true, returns true if found. */
-	bool DoWithDropSpenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cDropSpenserCallback & a_Callback);  // Lua-accessible
+	bool DoWithDropSpenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, cDropSpenserCallback & a_Callback);  // Lua-accessible
 
 	/** Calls the callback for the furnace at the specified coords.
 	Returns false if there's no furnace at those coords or callback returns true, returns true if found. */
-	bool DoWithFurnaceAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cFurnaceCallback & a_Callback);  // Lua-accessible
+	bool DoWithFurnaceAt(int a_BlockX, int a_BlockY, int a_BlockZ, cFurnaceCallback & a_Callback);  // Lua-accessible
 
 	/** Calls the callback for the noteblock at the specified coords.
 	Returns false if there's no noteblock at those coords or callback returns true, returns true if found. */
-	bool DoWithNoteBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cNoteBlockCallback & a_Callback);  // Lua-accessible
+	bool DoWithNoteBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, cNoteBlockCallback & a_Callback);  // Lua-accessible
 
 	/** Calls the callback for the command block at the specified coords.
 	Returns false if there's no command block at those coords or callback returns true, returns true if found. */
-	bool DoWithCommandBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cCommandBlockCallback & a_Callback);  // Lua-accessible
+	bool DoWithCommandBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, cCommandBlockCallback & a_Callback);  // Lua-accessible
 
 	/** Calls the callback for the mob head block at the specified coords.
 	Returns false if there's no mob head block at those coords or callback returns true, returns true if found. */
-	bool DoWithMobHeadAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cMobHeadCallback & a_Callback);  // Lua-accessible
+	bool DoWithMobHeadAt(int a_BlockX, int a_BlockY, int a_BlockZ, cMobHeadCallback & a_Callback);  // Lua-accessible
 
 	/** Calls the callback for the flower pot at the specified coords.
 	Returns false if there's no flower pot at those coords or callback returns true, returns true if found. */
-	bool DoWithFlowerPotAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cFlowerPotCallback & a_Callback);  // Lua-accessible
+	bool DoWithFlowerPotAt(int a_BlockX, int a_BlockY, int a_BlockZ, cFlowerPotCallback & a_Callback);  // Lua-accessible
 
 	/** Retrieves the test on the sign at the specified coords.
 	Returns false if there's no sign at those coords, true if found. */
@@ -360,7 +363,7 @@ public:
 	bool ForEachChunkInRect(int a_MinChunkX, int a_MaxChunkX, int a_MinChunkZ, int a_MaxChunkZ, cChunkDataCallback & a_Callback);
 
 	/** Calls the callback for each loaded chunk. Returns true if all chunks have been processed successfully */
-	bool ForEachLoadedChunk(const std::function<bool(int, int)> & a_Callback);
+	bool ForEachLoadedChunk(std::function<bool(int, int)> a_Callback);
 
 	/** Writes the block area into the specified coords. Returns true if all chunks have been processed. Prefer cBlockArea::Write() instead. */
 	bool WriteBlockArea(cBlockArea & a_Area, int a_MinBlockX, int a_MinBlockY, int a_MinBlockZ, int a_DataTypes);
diff --git a/src/ClientHandle.cpp b/src/ClientHandle.cpp
index a0a77f522..a06650d89 100644
--- a/src/ClientHandle.cpp
+++ b/src/ClientHandle.cpp
@@ -1660,9 +1660,9 @@ void cClientHandle::HandleSlotSelected(Int16 a_SlotNum)
 
 void cClientHandle::HandleSpectate(const cUUID & a_PlayerUUID)
 {
-	m_Player->GetWorld()->DoWithPlayerByUUID(a_PlayerUUID, [=](cPlayer & a_ToSpectate)
+	m_Player->GetWorld()->DoWithPlayerByUUID(a_PlayerUUID, [=](cPlayer * a_ToSpectate)
 	{
-		m_Player->TeleportToEntity(a_ToSpectate);
+		m_Player->TeleportToEntity(*a_ToSpectate);
 		return true;
 	});
 }
@@ -1734,9 +1734,9 @@ void cClientHandle::HandleUseEntity(UInt32 a_TargetEntityID, bool a_IsLeftClick)
 	// If the player is a spectator, let him spectate
 	if (m_Player->IsGameModeSpectator() && a_IsLeftClick)
 	{
-		m_Player->GetWorld()->DoWithEntityByID(a_TargetEntityID, [=](cEntity & a_Entity)
+		m_Player->GetWorld()->DoWithEntityByID(a_TargetEntityID, [=](cEntity * a_Entity)
 		{
-			m_Player->AttachTo(&a_Entity);
+			m_Player->AttachTo(a_Entity);
 			return true;
 		});
 		return;
@@ -1745,18 +1745,20 @@ void cClientHandle::HandleUseEntity(UInt32 a_TargetEntityID, bool a_IsLeftClick)
 	// If it is a right click, call the entity's OnRightClicked() handler:
 	if (!a_IsLeftClick)
 	{
-		cWorld * World = m_Player->GetWorld();
-		World->DoWithEntityByID(a_TargetEntityID, [=](cEntity & a_Entity)
+		class cRclkEntity : public cEntityCallback
+		{
+			cPlayer & m_Player;
+			virtual bool Item(cEntity * a_Entity) override
 			{
 				if (
-					cPluginManager::Get()->CallHookPlayerRightClickingEntity(*m_Player, a_Entity) ||
+					cPluginManager::Get()->CallHookPlayerRightClickingEntity(m_Player, *a_Entity) ||
 					(
-						m_Player->IsGameModeSpectator() &&  // Spectators cannot interact with every entity
+						m_Player.IsGameModeSpectator() &&  // Spectators cannot interact with every entity
 						(
-							!a_Entity.IsMinecart() ||  // They can only interact with minecarts
+							!a_Entity->IsMinecart() ||  // They can only interact with minecarts
 							(
-								(static_cast<cMinecart &>(a_Entity).GetPayload() != cMinecart::mpChest) &&  // And only if the type matches a minecart with a chest or
-								(static_cast<cMinecart &>(a_Entity).GetPayload() != cMinecart::mpHopper)    // a minecart with a hopper
+								(reinterpret_cast<cMinecart *>(a_Entity)->GetPayload() != cMinecart::mpChest) &&  // And only if the type matches a minecart with a chest or
+								(reinterpret_cast<cMinecart *>(a_Entity)->GetPayload() != cMinecart::mpHopper)    // a minecart with a hopper
 							)
 						)
 					)
@@ -1764,34 +1766,52 @@ void cClientHandle::HandleUseEntity(UInt32 a_TargetEntityID, bool a_IsLeftClick)
 				{
 					return false;
 				}
-				a_Entity.OnRightClicked(*m_Player);
+				a_Entity->OnRightClicked(m_Player);
 				return false;
 			}
-		);
+		public:
+			cRclkEntity(cPlayer & a_Player) : m_Player(a_Player) {}
+		} Callback (*m_Player);
+
+		cWorld * World = m_Player->GetWorld();
+		World->DoWithEntityByID(a_TargetEntityID, Callback);
 		return;
 	}
 
 	// If it is a left click, attack the entity:
-	m_Player->GetWorld()->DoWithEntityByID(a_TargetEntityID, [=](cEntity & a_Entity)
+	class cDamageEntity : public cEntityCallback
+	{
+	public:
+		cPlayer * m_Me;
+
+		cDamageEntity(cPlayer * a_Player) :
+			m_Me(a_Player)
+		{
+		}
+
+		virtual bool Item(cEntity * a_Entity) override
 		{
-			if (!a_Entity.GetWorld()->IsPVPEnabled())
+			if (!a_Entity->GetWorld()->IsPVPEnabled())
 			{
 				// PVP is disabled, disallow players hurting other players:
-				if (a_Entity.IsPlayer())
+				if (a_Entity->IsPlayer())
 				{
 					// Player is hurting another player which is not allowed when PVP is disabled so ignore it
 					return true;
 				}
 			}
-			a_Entity.TakeDamage(*m_Player);
-			m_Player->AddFoodExhaustion(0.3);
-			if (a_Entity.IsPawn())
+			a_Entity->TakeDamage(*m_Me);
+			m_Me->AddFoodExhaustion(0.3);
+			if (a_Entity->IsPawn())
 			{
-				m_Player->NotifyNearbyWolves(static_cast<cPawn*>(&a_Entity), true);
+				m_Me->NotifyNearbyWolves(static_cast<cPawn*>(a_Entity), true);
 			}
 			return true;
 		}
-	);
+	} Callback(m_Player);
+
+	cWorld * World = m_Player->GetWorld();
+	World->DoWithEntityByID(a_TargetEntityID, Callback);
 }
 
 
@@ -1840,8 +1860,17 @@ bool cClientHandle::CheckMultiLogin(const AString & a_Username)
 		return false;
 	}
 
+	class cCallback :
+		public cPlayerListCallback
+	{
+		virtual bool Item(cPlayer * a_Player) override
+		{
+			return true;
+		}
+	} Callback;
+
 	// Check if the player is in any World.
-	if (cRoot::Get()->DoWithPlayer(a_Username, [](cPlayer &) { return true; }))
+	if (cRoot::Get()->DoWithPlayer(a_Username, Callback))
 	{
 		Kick("A player of the username is already logged in");
 		return false;
diff --git a/src/DeadlockDetect.cpp b/src/DeadlockDetect.cpp
index 411d452f6..df14e610b 100644
--- a/src/DeadlockDetect.cpp
+++ b/src/DeadlockDetect.cpp
@@ -56,12 +56,25 @@ bool cDeadlockDetect::Start(int a_IntervalSec)
 	m_IntervalSec = a_IntervalSec;
 
 	// Read the initial world data:
-	cRoot::Get()->ForEachWorld([=](cWorld & a_World)
+	class cFillIn :
+		public cWorldListCallback
+	{
+	public:
+		cFillIn(cDeadlockDetect * a_Detect) :
+			m_Detect(a_Detect)
+		{
+		}
+
+		virtual bool Item(cWorld * a_World) override
 		{
-			SetWorldAge(a_World.GetName(), a_World.GetWorldAge());
+			m_Detect->SetWorldAge(a_World->GetName(), a_World->GetWorldAge());
 			return false;
 		}
-	);
+
+	protected:
+		cDeadlockDetect * m_Detect;
+	} FillIn(this);
+	cRoot::Get()->ForEachWorld(FillIn);
 	return super::Start();
 }
 
@@ -102,12 +115,25 @@ void cDeadlockDetect::Execute(void)
 	while (!m_ShouldTerminate)
 	{
 		// Check the world ages:
-		cRoot::Get()->ForEachWorld([=](cWorld & a_World)
+		class cChecker :
+			public cWorldListCallback
+		{
+		public:
+			cChecker(cDeadlockDetect * a_Detect) :
+				m_Detect(a_Detect)
+			{
+			}
+
+		protected:
+			cDeadlockDetect * m_Detect;
+
+			virtual bool Item(cWorld * a_World) override
 			{
-				CheckWorldAge(a_World.GetName(), a_World.GetWorldAge());
+				m_Detect->CheckWorldAge(a_World->GetName(), a_World->GetWorldAge());
 				return false;
 			}
-		);
+		} Checker(this);
+		cRoot::Get()->ForEachWorld(Checker);
 
 		std::this_thread::sleep_for(std::chrono::milliseconds(CYCLE_MILLISECONDS));
 	}  // while (should run)
diff --git a/src/Entities/Entity.cpp b/src/Entities/Entity.cpp
index 956534856..5f6b81497 100644
--- a/src/Entities/Entity.cpp
+++ b/src/Entities/Entity.cpp
@@ -306,22 +306,38 @@ void cEntity::TakeDamage(eDamageType a_DamageType, cEntity * a_Attacker, int a_R
 
 void cEntity::TakeDamage(eDamageType a_DamageType, UInt32 a_AttackerID, int a_RawDamage, double a_KnockbackAmount)
 {
-	m_World->DoWithEntityByID(a_AttackerID, [=](cEntity & a_Attacker)
+	class cFindEntity : public cEntityCallback
+	{
+	public:
+
+		cEntity * m_Entity;
+		eDamageType m_DamageType;
+		int m_RawDamage;
+		double m_KnockbackAmount;
+
+		virtual bool Item(cEntity * a_Attacker) override
 		{
 			cPawn * Attacker;
-			if (a_Attacker.IsPawn())
+			if (a_Attacker->IsPawn())
 			{
-				Attacker = static_cast<cPawn*>(&a_Attacker);
+				Attacker = static_cast<cPawn*>(a_Attacker);
 			}
 			else
 			{
 				Attacker = nullptr;
 			}
 
-			TakeDamage(a_DamageType, Attacker, a_RawDamage, a_KnockbackAmount);
+
+			m_Entity->TakeDamage(m_DamageType, Attacker, m_RawDamage, m_KnockbackAmount);
 			return true;
 		}
-	);
+	} Callback;
+
+	Callback.m_Entity = this;
+	Callback.m_DamageType = a_DamageType;
+	Callback.m_RawDamage = a_RawDamage;
+	Callback.m_KnockbackAmount = a_KnockbackAmount;
+	m_World->DoWithEntityByID(a_AttackerID, Callback);
 }
 
 
@@ -652,7 +668,7 @@ bool cEntity::ArmorCoversAgainst(eDamageType a_DamageType)
 
 int cEntity::GetEnchantmentCoverAgainst(const cEntity * a_Attacker, eDamageType a_DamageType, int a_Damage)
 {
-	int TotalEPF = 0;
+	int TotalEPF = 0.0;
 
 	const cItem ArmorItems[] = { GetEquippedHelmet(), GetEquippedChestplate(), GetEquippedLeggings(), GetEquippedBoots() };
 	for (size_t i = 0; i < ARRAYCOUNT(ArmorItems); i++)
diff --git a/src/Entities/Floater.cpp b/src/Entities/Floater.cpp
index de5824068..eeaa6cf3d 100644
--- a/src/Entities/Floater.cpp
+++ b/src/Entities/Floater.cpp
@@ -13,7 +13,8 @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // cFloaterEntityCollisionCallback
-class cFloaterEntityCollisionCallback
+class cFloaterEntityCollisionCallback :
+	public cEntityCallback
 {
 public:
 	cFloaterEntityCollisionCallback(cFloater * a_Floater, const Vector3d & a_Pos, const Vector3d & a_NextPos) :
@@ -24,14 +25,14 @@ public:
 		m_HitEntity(nullptr)
 	{
 	}
-	bool operator () (cEntity & a_Entity)
+	virtual bool Item(cEntity * a_Entity) override
 	{
-		if (!a_Entity.IsMob())  // Floaters can only pull mobs not other entities.
+		if (!a_Entity->IsMob())  // Floaters can only pull mobs not other entities.
 		{
 			return false;
 		}
 
-		cBoundingBox EntBox(a_Entity.GetPosition(), a_Entity.GetWidth() / 2, a_Entity.GetHeight());
+		cBoundingBox EntBox(a_Entity->GetPosition(), a_Entity->GetWidth() / 2, a_Entity->GetHeight());
 
 		double LineCoeff;
 		eBlockFace Face;
@@ -46,7 +47,7 @@ public:
 		{
 			// The entity is closer than anything we've stored so far, replace it as the potential victim
 			m_MinCoeff = LineCoeff;
-			m_HitEntity = &a_Entity;
+			m_HitEntity = a_Entity;
 		}
 
 		// Don't break the enumeration, we want all the entities
@@ -74,6 +75,32 @@ protected:
 
 
 
+////////////////////////////////////////////////////////////////////////////////
+// cFloaterCheckEntityExist
+class cFloaterCheckEntityExist :
+	public cEntityCallback
+{
+public:
+	cFloaterCheckEntityExist(void) :
+		m_EntityExists(false)
+	{
+	}
+
+	bool Item(cEntity * a_Entity) override
+	{
+		m_EntityExists = true;
+		return false;
+	}
+
+	bool DoesExist(void) const { return m_EntityExists; }
+protected:
+	bool m_EntityExists;
+} ;
+
+
+
+
+
 cFloater::cFloater(double a_X, double a_Y, double a_Z, Vector3d a_Speed, UInt32 a_PlayerID, int a_CountDownTime) :
 	cEntity(etFloater, a_X, a_Y, a_Z, 0.2, 0.2),
 	m_BitePos(Vector3d(a_X, a_Y, a_Z)),
@@ -173,16 +200,18 @@ void cFloater::Tick(std::chrono::milliseconds a_Dt, cChunk & a_Chunk)
 		}
 	}
 
-	if (!m_World->DoWithEntityByID(m_PlayerID, [](cEntity &) { return true; }))  // The owner doesn't exist anymore. Destroy the floater entity.
+	cFloaterCheckEntityExist EntityCallback;
+	m_World->DoWithEntityByID(m_PlayerID, EntityCallback);
+	if (!EntityCallback.DoesExist())  // The owner doesn't exist anymore. Destroy the floater entity.
 	{
 		Destroy(true);
 	}
 
 	if (m_AttachedMobID != cEntity::INVALID_ID)
 	{
-		if (!m_World->DoWithEntityByID(m_AttachedMobID, [](cEntity &) { return true; }))
+		m_World->DoWithEntityByID(m_AttachedMobID, EntityCallback);  // The mob the floater was attached to doesn't exist anymore.
+		if (!EntityCallback.DoesExist())
 		{
-			// The mob the floater was attached to doesn't exist anymore.
 			m_AttachedMobID = cEntity::INVALID_ID;
 		}
 	}
diff --git a/src/Entities/LeashKnot.cpp b/src/Entities/LeashKnot.cpp
index 51002531d..a86dc9d53 100644
--- a/src/Entities/LeashKnot.cpp
+++ b/src/Entities/LeashKnot.cpp
@@ -1,4 +1,4 @@
-
+
 #include "Globals.h"  // NOTE: MSVC stupidness requires this to be the same across all modules
 
 #include "LeashKnot.h"
@@ -38,42 +38,58 @@ void cLeashKnot::OnRightClicked(cPlayer & a_Player)
 
 
 
-void cLeashKnot::TiePlayersLeashedMobs(cPlayer & a_Player, bool a_ShouldBroadcast)
+void cLeashKnot::TiePlayersLeashedMobs(cPlayer & a_Player, bool a_ShouldBroadCast)
 {
 	// Check leashed nearby mobs to tie them to this knot
-	// taking world from player (instead from this) because this can be called before entity was initialized
-	a_Player.GetWorld()->ForEachEntityInBox(cBoundingBox(GetPosition(), 8, 8, -4), [&](cEntity & a_Entity)
+	class LookForLeasheds : public cEntityCallback
+	{
+	public:
+		cLeashKnot * m_Knot;
+		cPlayer * m_Player;
+		bool m_ShouldBroadcast;
+
+		LookForLeasheds(cLeashKnot * a_Knot, cPlayer * a_PlayerLeashedTo, bool a_ShouldBroadcast) :
+			m_Knot(a_Knot),
+			m_Player(a_PlayerLeashedTo),
+			m_ShouldBroadcast(a_ShouldBroadcast)
+		{
+		}
+
+		virtual bool Item(cEntity * a_Entity) override
 		{
 			// If the entity is not a monster skip it
-			if (a_Entity.GetEntityType() != cEntity::eEntityType::etMonster)
+			if (a_Entity->GetEntityType() != cEntity::eEntityType::etMonster)
 			{
 				return false;
 			}
 
-			auto & PotentialLeashed = static_cast<cMonster&>(a_Entity);
+			cMonster * PotentialLeashed = static_cast<cMonster*>(a_Entity);
 
 			// If can't be leashed skip it
-			if (!PotentialLeashed.CanBeLeashed())
+			if (!PotentialLeashed->CanBeLeashed())
 			{
 				return false;
 			}
 
 			// If it's not leashed to the player skip it
 			if (
-				!PotentialLeashed.IsLeashed() ||
-				!PotentialLeashed.GetLeashedTo()->IsPlayer() ||
-				(PotentialLeashed.GetLeashedTo()->GetUniqueID() != a_Player.GetUniqueID())
+				!PotentialLeashed->IsLeashed() ||
+				!PotentialLeashed->GetLeashedTo()->IsPlayer() ||
+				(PotentialLeashed->GetLeashedTo()->GetUniqueID() != m_Player->GetUniqueID())
 			)
 			{
 				return false;
 			}
 
 			// All conditions met, unleash from player and leash to fence
-			PotentialLeashed.Unleash(false, false);
-			PotentialLeashed.LeashTo(*this, a_ShouldBroadcast);
+			PotentialLeashed->Unleash(false, false);
+			PotentialLeashed->LeashTo(*m_Knot, m_ShouldBroadcast);
 			return false;
 		}
-	);
+	} LookForLeashedsCallback(this, &a_Player, a_ShouldBroadCast);
+
+	// taking world from player (instead from this) because this can be called before entity was initialized
+	a_Player.GetWorld()->ForEachEntityInBox(cBoundingBox(GetPosition(), 8, 8, -4), LookForLeashedsCallback);
 }
 
 
@@ -142,19 +158,26 @@ void cLeashKnot::Tick(std::chrono::milliseconds a_Dt, cChunk & a_Chunk)
 
 cLeashKnot * cLeashKnot::FindKnotAtPos(cWorldInterface & a_WorldInterface, Vector3i a_BlockPos)
 {
-	cLeashKnot * LeashKnot = nullptr;
-	a_WorldInterface.ForEachEntityInBox(cBoundingBox(a_BlockPos, 0.5, 1), [&](cEntity & a_Entity)
+	class LookForKnot : public cEntityCallback
+	{
+	public:
+		cLeashKnot * m_LeashKnot = nullptr;
+
+		virtual bool Item(cEntity * a_Entity) override
 		{
-			if (a_Entity.IsLeashKnot())
+			if (a_Entity->IsLeashKnot())
 			{
-				LeashKnot = static_cast<cLeashKnot *>(&a_Entity);
+				m_LeashKnot = reinterpret_cast<cLeashKnot *>(a_Entity);
 				return true;
 			}
 			return false;
 		}
-	);
 
-	return LeashKnot;
+	} CallbackFindKnot;
+
+	a_WorldInterface.ForEachEntityInBox(cBoundingBox(a_BlockPos, 0.5, 1), CallbackFindKnot);
+
+	return CallbackFindKnot.m_LeashKnot;
 }
 
 
diff --git a/src/Entities/Minecart.cpp b/src/Entities/Minecart.cpp
index 8921f8894..7f32dc910 100644
--- a/src/Entities/Minecart.cpp
+++ b/src/Entities/Minecart.cpp
@@ -20,7 +20,8 @@
 
 
 
-class cMinecartCollisionCallback
+class cMinecartCollisionCallback :
+	public cEntityCallback
 {
 public:
 	cMinecartCollisionCallback(Vector3d a_Pos, double a_Height, double a_Width, UInt32 a_UniqueID, UInt32 a_AttacheeUniqueID) :
@@ -34,31 +35,33 @@ public:
 	{
 	}
 
-	bool operator () (cEntity & a_Entity)
+	virtual bool Item(cEntity * a_Entity) override
 	{
+		ASSERT(a_Entity != nullptr);
+
 		if (
 			(
-				!a_Entity.IsPlayer() ||
-				static_cast<cPlayer &>(a_Entity).IsGameModeSpectator()  // Spectators doesn't collide with anything
+				!a_Entity->IsPlayer() ||
+				reinterpret_cast<cPlayer *>(a_Entity)->IsGameModeSpectator()  // Spectators doesn't collide with anything
 			) &&
-			!a_Entity.IsMob() &&
-			!a_Entity.IsMinecart() &&
-			!a_Entity.IsBoat()
+			!a_Entity->IsMob() &&
+			!a_Entity->IsMinecart() &&
+			!a_Entity->IsBoat()
 		)
 		{
 			return false;
 		}
-		else if ((a_Entity.GetUniqueID() == m_UniqueID) || (a_Entity.GetUniqueID() == m_AttacheeUniqueID))
+		else if ((a_Entity->GetUniqueID() == m_UniqueID) || (a_Entity->GetUniqueID() == m_AttacheeUniqueID))
 		{
 			return false;
 		}
 
-		cBoundingBox bbEntity(a_Entity.GetPosition(), a_Entity.GetWidth() / 2, a_Entity.GetHeight());
+		cBoundingBox bbEntity(a_Entity->GetPosition(), a_Entity->GetWidth() / 2, a_Entity->GetHeight());
 		cBoundingBox bbMinecart(Vector3d(m_Pos.x, floor(m_Pos.y), m_Pos.z), m_Width / 2, m_Height);
 
 		if (bbEntity.DoesIntersect(bbMinecart))
 		{
-			m_CollidedEntityPos = a_Entity.GetPosition();
+			m_CollidedEntityPos = a_Entity->GetPosition();
 			m_DoesIntersect = true;
 			return true;
 		}
diff --git a/src/Entities/Pawn.cpp b/src/Entities/Pawn.cpp
index ac8e4b1ab..0fa11997b 100644
--- a/src/Entities/Pawn.cpp
+++ b/src/Entities/Pawn.cpp
@@ -1,4 +1,4 @@
-
+
 #include "Globals.h"  // NOTE: MSVC stupidness requires this to be the same across all modules
 
 #include "Pawn.h"
@@ -79,37 +79,49 @@ void cPawn::Tick(std::chrono::milliseconds a_Dt, cChunk & a_Chunk)
 		Effect->OnTick(*this);
 	}
 
-	// Spectators cannot push entities around
-	if ((!IsPlayer()) || (!static_cast<cPlayer *>(this)->IsGameModeSpectator()))
+	class Pusher : public cEntityCallback
 	{
-		m_World->ForEachEntityInBox(cBoundingBox(GetPosition(), GetWidth(), GetHeight()), [=](cEntity & a_Entity)
+	public:
+		cEntity * m_Pusher;
+
+		Pusher(cEntity * a_Pusher) :
+			m_Pusher(a_Pusher)
+		{
+		}
+
+		virtual bool Item(cEntity * a_Entity) override
+		{
+			if (a_Entity->GetUniqueID() == m_Pusher->GetUniqueID())
+			{
+				return false;
+			}
+
+			// we only push other mobs, boats and minecarts
+			if ((a_Entity->GetEntityType() != etMonster) && (a_Entity->GetEntityType() != etMinecart) && (a_Entity->GetEntityType() != etBoat))
 			{
-				if (a_Entity.GetUniqueID() == GetUniqueID())
-				{
-					return false;
-				}
-
-				// we only push other mobs, boats and minecarts
-				if ((a_Entity.GetEntityType() != etMonster) && (a_Entity.GetEntityType() != etMinecart) && (a_Entity.GetEntityType() != etBoat))
-				{
-					return false;
-				}
-
-				// do not push a boat / minecart you're sitting in
-				if (IsAttachedTo(&a_Entity))
-				{
-					return false;
-				}
-
-				Vector3d v3Delta = a_Entity.GetPosition() - GetPosition();
-				v3Delta.y = 0.0;  // we only push sideways
-				v3Delta *= 1.0 / (v3Delta.Length() + 0.01);  // we push harder if we're close
-				// QUESTION: is there an additional multiplier for this? current shoving seems a bit weak
-
-				a_Entity.AddSpeed(v3Delta);
 				return false;
 			}
-		);
+
+			// do not push a boat / minecart you're sitting in
+			if (m_Pusher->IsAttachedTo(a_Entity))
+			{
+				return false;
+			}
+
+			Vector3d v3Delta = a_Entity->GetPosition() - m_Pusher->GetPosition();
+			v3Delta.y = 0.0;  // we only push sideways
+			v3Delta *= 1.0 / (v3Delta.Length() + 0.01);  // we push harder if we're close
+			// QUESTION: is there an additional multiplier for this? current shoving seems a bit weak
+
+			a_Entity->AddSpeed(v3Delta);
+			return false;
+		}
+	} Callback(this);
+
+	// Spectators cannot push entities around
+	if ((!IsPlayer()) || (!reinterpret_cast<cPlayer *>(this)->IsGameModeSpectator()))
+	{
+		m_World->ForEachEntityInBox(cBoundingBox(GetPosition(), GetWidth(), GetHeight()), Callback);
 	}
 
 	super::Tick(a_Dt, a_Chunk);
diff --git a/src/Entities/Pickup.cpp b/src/Entities/Pickup.cpp
index fcae586f6..0c6c8feab 100644
--- a/src/Entities/Pickup.cpp
+++ b/src/Entities/Pickup.cpp
@@ -17,7 +17,8 @@
 
 
 
-class cPickupCombiningCallback
+class cPickupCombiningCallback :
+	public cEntityCallback
 {
 public:
 	cPickupCombiningCallback(Vector3d a_Position, cPickup * a_Pickup) :
@@ -27,21 +28,21 @@ public:
 	{
 	}
 
-	bool operator () (cEntity & a_Entity)
+	virtual bool Item(cEntity * a_Entity) override
 	{
-		ASSERT(a_Entity.IsTicking());
-		if (!a_Entity.IsPickup() || (a_Entity.GetUniqueID() <= m_Pickup->GetUniqueID()) || !a_Entity.IsOnGround())
+		ASSERT(a_Entity->IsTicking());
+		if (!a_Entity->IsPickup() || (a_Entity->GetUniqueID() <= m_Pickup->GetUniqueID()) || !a_Entity->IsOnGround())
 		{
 			return false;
 		}
 
 
-		Vector3d EntityPos = a_Entity.GetPosition();
+		Vector3d EntityPos = a_Entity->GetPosition();
 		double Distance = (EntityPos - m_Position).Length();
 
-		auto & OtherPickup = static_cast<cPickup &>(a_Entity);
-		cItem & Item = OtherPickup.GetItem();
-		if ((Distance < 1.2) && Item.IsEqual(m_Pickup->GetItem()) && OtherPickup.CanCombine())
+		cPickup * OtherPickup = static_cast<cPickup *>(a_Entity);
+		cItem & Item = OtherPickup->GetItem();
+		if ((Distance < 1.2) && Item.IsEqual(m_Pickup->GetItem()) && OtherPickup->CanCombine())
 		{
 			short CombineCount = Item.m_ItemCount;
 			if ((CombineCount + m_Pickup->GetItem().m_ItemCount) > Item.GetMaxStackSize())
@@ -63,16 +64,16 @@ public:
 				int DiffX = FloorC(m_Pickup->GetPosX() * 32.0) - FloorC(EntityPos.x * 32.0);
 				int DiffY = FloorC(m_Pickup->GetPosY() * 32.0) - FloorC(EntityPos.y * 32.0);
 				int DiffZ = FloorC(m_Pickup->GetPosZ() * 32.0) - FloorC(EntityPos.z * 32.0);
-				a_Entity.GetWorld()->BroadcastEntityRelMove(a_Entity, static_cast<char>(DiffX), static_cast<char>(DiffY), static_cast<char>(DiffZ));
+				a_Entity->GetWorld()->BroadcastEntityRelMove(*a_Entity, static_cast<char>(DiffX), static_cast<char>(DiffY), static_cast<char>(DiffZ));
 				/* End of experimental animation */
-				a_Entity.Destroy();
+				a_Entity->Destroy();
 
 				// Reset the timer
 				m_Pickup->SetAge(0);
 			}
 			else
 			{
-				a_Entity.GetWorld()->BroadcastEntityMetadata(a_Entity);
+				a_Entity->GetWorld()->BroadcastEntityMetadata(*a_Entity);
 			}
 			m_FoundMatchingPickup = true;
 		}
diff --git a/src/Entities/Player.cpp b/src/Entities/Player.cpp
index f17d53b42..4189841b8 100644
--- a/src/Entities/Player.cpp
+++ b/src/Entities/Player.cpp
@@ -1005,21 +1005,36 @@ bool cPlayer::DoTakeDamage(TakeDamageInfo & a_TDI)
 void cPlayer::NotifyNearbyWolves(cPawn * a_Opponent, bool a_IsPlayerInvolved)
 {
 	ASSERT(a_Opponent != nullptr);
+	class LookForWolves : public cEntityCallback
+	{
+	public:
+		cPlayer * m_Player;
+		cPawn * m_Attacker;
+		bool m_IsPlayerInvolved;
+
+		LookForWolves(cPlayer * a_Me, cPawn * a_MyAttacker, bool a_PlayerInvolved) :
+			m_Player(a_Me),
+			m_Attacker(a_MyAttacker),
+			m_IsPlayerInvolved(a_PlayerInvolved)
+		{
+		}
 
-	m_World->ForEachEntityInBox(cBoundingBox(GetPosition(), 16), [&] (cEntity & a_Entity)
+		virtual bool Item(cEntity * a_Entity) override
 		{
-			if (a_Entity.IsMob())
+			if (a_Entity->IsMob())
 			{
-				auto & Mob = static_cast<cMonster&>(a_Entity);
-				if (Mob.GetMobType() == mtWolf)
+				cMonster * Mob = static_cast<cMonster*>(a_Entity);
+				if (Mob->GetMobType() == mtWolf)
 				{
-					auto & Wolf = static_cast<cWolf&>(Mob);
-					Wolf.ReceiveNearbyFightInfo(GetUUID(), a_Opponent, a_IsPlayerInvolved);
+					cWolf * Wolf = static_cast<cWolf*>(Mob);
+					Wolf->ReceiveNearbyFightInfo(m_Player->GetUUID(), m_Attacker, m_IsPlayerInvolved);
 				}
 			}
 			return false;
 		}
-	);
+	} Callback(this, a_Opponent, a_IsPlayerInvolved);
+
+	m_World->ForEachEntityInBox(cBoundingBox(GetPosition(), 16), Callback);
 }
 
 
@@ -2417,12 +2432,17 @@ void cPlayer::HandleFloater()
 	{
 		return;
 	}
-	m_World->DoWithEntityByID(m_FloaterID, [](cEntity & a_Entity)
+	class cFloaterCallback :
+		public cEntityCallback
+	{
+	public:
+		virtual bool Item(cEntity * a_Entity) override
 		{
-			a_Entity.Destroy(true);
+			a_Entity->Destroy(true);
 			return true;
 		}
-	);
+	} Callback;
+	m_World->DoWithEntityByID(m_FloaterID, Callback);
 	SetIsFishing(false);
 }
 
@@ -2666,18 +2686,29 @@ bool cPlayer::DoesPlacingBlocksIntersectEntity(const sSetBlockVector & a_Blocks)
 	cWorld * World = GetWorld();
 
 	// Check to see if any entity intersects any block being placed
-	return !World->ForEachEntityInBox(PlacingBounds, [&](cEntity & a_Entity)
+	class DoesIntersectBlock : public cEntityCallback
+	{
+	public:
+		const std::vector<cBoundingBox> & m_BoundingBoxes;
+
+		// The distance inside the block the entity can still be.
+		const double EPSILON = 0.0005;
+
+		DoesIntersectBlock(const std::vector<cBoundingBox> & a_BoundingBoxes) :
+			m_BoundingBoxes(a_BoundingBoxes)
 		{
-			// The distance inside the block the entity can still be.
-			const double EPSILON = 0.0005;
+		}
 
-			if (!a_Entity.DoesPreventBlockPlacement())
+		virtual bool Item(cEntity * a_Entity) override
+		{
+			if (!a_Entity->DoesPreventBlockPlacement())
 			{
 				return false;
 			}
-			cBoundingBox EntBox(a_Entity.GetPosition(), a_Entity.GetWidth() / 2, a_Entity.GetHeight());
-			for (auto BlockBox : PlacementBoxes)
+			cBoundingBox EntBox(a_Entity->GetPosition(), a_Entity->GetWidth() / 2, a_Entity->GetHeight());
+			for (auto BlockBox: m_BoundingBoxes)
 			{
+
 				// Put in a little bit of wiggle room
 				BlockBox.Expand(-EPSILON, -EPSILON, -EPSILON);
 				if (EntBox.DoesIntersect(BlockBox))
@@ -2687,7 +2718,15 @@ bool cPlayer::DoesPlacingBlocksIntersectEntity(const sSetBlockVector & a_Blocks)
 			}
 			return false;
 		}
-	);
+	} Callback(PlacementBoxes);
+
+	// See if any entities in that bounding box collide with anyone
+	if (!World->ForEachEntityInBox(PlacingBounds, Callback))
+	{
+		return true;
+	}
+
+	return false;
 }
 
 
diff --git a/src/Entities/ProjectileEntity.cpp b/src/Entities/ProjectileEntity.cpp
index 13ebe31bc..c2a1f782d 100644
--- a/src/Entities/ProjectileEntity.cpp
+++ b/src/Entities/ProjectileEntity.cpp
@@ -126,7 +126,8 @@ protected:
 ////////////////////////////////////////////////////////////////////////////////
 // cProjectileEntityCollisionCallback:
 
-class cProjectileEntityCollisionCallback
+class cProjectileEntityCollisionCallback :
+	public cEntityCallback
 {
 public:
 	cProjectileEntityCollisionCallback(cProjectileEntity * a_Projectile, const Vector3d & a_Pos, const Vector3d & a_NextPos) :
@@ -139,11 +140,11 @@ public:
 	}
 
 
-	bool operator () (cEntity & a_Entity)
+	virtual bool Item(cEntity * a_Entity) override
 	{
 		if (
-			(&a_Entity == m_Projectile) ||          // Do not check collisions with self
-			(a_Entity.GetUniqueID() == m_Projectile->GetCreatorUniqueID())  // Do not check whoever shot the projectile
+			(a_Entity == m_Projectile) ||          // Do not check collisions with self
+			(a_Entity->GetUniqueID() == m_Projectile->GetCreatorUniqueID())  // Do not check whoever shot the projectile
 		)
 		{
 			// Don't check creator only for the first 5 ticks so that projectiles can collide with the creator
@@ -153,7 +154,7 @@ public:
 			}
 		}
 
-		cBoundingBox EntBox(a_Entity.GetPosition(), a_Entity.GetWidth() / 2, a_Entity.GetHeight());
+		cBoundingBox EntBox(a_Entity->GetPosition(), a_Entity->GetWidth() / 2, a_Entity->GetHeight());
 
 		// Instead of colliding the bounding box with another bounding box in motion, we collide an enlarged bounding box with a hairline.
 		// The results should be good enough for our purposes
@@ -167,20 +168,20 @@ public:
 		}
 
 		if (
-			!a_Entity.IsMob() &&
-			!a_Entity.IsMinecart() &&
+			!a_Entity->IsMob() &&
+			!a_Entity->IsMinecart() &&
 			(
-				!a_Entity.IsPlayer() ||
-				static_cast<cPlayer &>(a_Entity).IsGameModeSpectator()
+				!a_Entity->IsPlayer() ||
+				static_cast<cPlayer *>(a_Entity)->IsGameModeSpectator()
 			) &&
-			!a_Entity.IsBoat()
+			!a_Entity->IsBoat()
 		)
 		{
 			// Not an entity that interacts with a projectile
 			return false;
 		}
 
-		if (cPluginManager::Get()->CallHookProjectileHitEntity(*m_Projectile, a_Entity))
+		if (cPluginManager::Get()->CallHookProjectileHitEntity(*m_Projectile, *a_Entity))
 		{
 			// A plugin disagreed.
 			return false;
@@ -190,7 +191,7 @@ public:
 		{
 			// The entity is closer than anything we've stored so far, replace it as the potential victim
 			m_MinCoeff = LineCoeff;
-			m_HitEntity = &a_Entity;
+			m_HitEntity = a_Entity;
 		}
 
 		// Don't break the enumeration, we want all the entities
@@ -326,13 +327,20 @@ void cProjectileEntity::OnHitEntity(cEntity & a_EntityHit, const Vector3d & a_Hi
 	// If we were created by a player and we hit a pawn, notify attacking player's wolves
 	if (a_EntityHit.IsPawn() && (GetCreatorName() != ""))
 	{
-		auto EntityHit = static_cast<cPawn *>(&a_EntityHit);
-		m_World->DoWithEntityByID(GetCreatorUniqueID(), [=](cEntity & a_Hitter)
+		class cNotifyWolves : public cEntityCallback
+		{
+		public:
+			cPawn * m_EntityHit;
+
+			virtual bool Item(cEntity * a_Hitter) override
 			{
-				static_cast<cPlayer&>(a_Hitter).NotifyNearbyWolves(EntityHit, true);
+				static_cast<cPlayer*>(a_Hitter)->NotifyNearbyWolves(m_EntityHit, true);
 				return true;
 			}
-		);
+		} Callback;
+
+		Callback.m_EntityHit = static_cast<cPawn*>(&a_EntityHit);
+		m_World->DoWithEntityByID(GetCreatorUniqueID(), Callback);
 	}
 }
 
diff --git a/src/Entities/SplashPotionEntity.cpp b/src/Entities/SplashPotionEntity.cpp
index 35afe0fea..af4008e83 100644
--- a/src/Entities/SplashPotionEntity.cpp
+++ b/src/Entities/SplashPotionEntity.cpp
@@ -17,6 +17,60 @@
 
 
 ////////////////////////////////////////////////////////////////////////////////
+// cSplashPotionEntityCallback:
+
+/** Used to distribute the splashed potion effect among nearby entities */
+class cSplashPotionCallback :
+	public cEntityCallback
+{
+public:
+	/** Creates the callback.
+	@param a_HitPos            The position where the splash potion has splashed
+	@param a_EntityEffectType  The effect type of the potion
+	@param a_EntityEffect      The effect description */
+	cSplashPotionCallback(const Vector3d & a_HitPos, cEntityEffect::eType a_EntityEffectType, const cEntityEffect & a_EntityEffect) :
+		m_HitPos(a_HitPos),
+		m_EntityEffectType(a_EntityEffectType),
+		m_EntityEffect(a_EntityEffect)
+	{
+	}
+
+	/** Called by cWorld::ForEachEntity(), adds the stored entity effect to the entity, if it is close enough. */
+	virtual bool Item(cEntity * a_Entity) override
+	{
+		if (!a_Entity->IsPawn())
+		{
+			// Not an entity that can take effects
+			return false;
+		}
+
+		double SplashDistance = (a_Entity->GetPosition() - m_HitPos).Length();
+		if (SplashDistance >= 20)
+		{
+			// Too far away
+			return false;
+		}
+
+		// y = -0.25x + 1, where x is the distance from the player. Approximation for potion splash.
+		// TODO: better equation
+		double Reduction = -0.25 * SplashDistance + 1.0;
+		Reduction = std::max(Reduction, 0.0);
+
+		static_cast<cPawn *>(a_Entity)->AddEntityEffect(m_EntityEffectType, m_EntityEffect.GetDuration(), m_EntityEffect.GetIntensity(), Reduction);
+		return false;
+	}
+
+private:
+	const Vector3d & m_HitPos;
+	cEntityEffect::eType m_EntityEffectType;
+	const cEntityEffect & m_EntityEffect;
+};
+
+
+
+
+
+////////////////////////////////////////////////////////////////////////////////
 // cSplashPotionEntity:
 
 cSplashPotionEntity::cSplashPotionEntity(
@@ -65,30 +119,8 @@ void cSplashPotionEntity::OnHitEntity(cEntity & a_EntityHit, const Vector3d & a_
 
 void cSplashPotionEntity::Splash(const Vector3d & a_HitPos)
 {
-	m_World->ForEachEntity([=](cEntity & a_Entity)
-		{
-			if (!a_Entity.IsPawn())
-			{
-				// Not an entity that can take effects
-				return false;
-			}
-
-			double SplashDistance = (a_Entity.GetPosition() - a_HitPos).Length();
-			if (SplashDistance >= 20)
-			{
-				// Too far away
-				return false;
-			}
-
-			// y = -0.25x + 1, where x is the distance from the player. Approximation for potion splash.
-			// TODO: better equation
-			double Reduction = -0.25 * SplashDistance + 1.0;
-			Reduction = std::max(Reduction, 0.0);
-
-			static_cast<cPawn &>(a_Entity).AddEntityEffect(m_EntityEffectType, m_EntityEffect.GetDuration(), m_EntityEffect.GetIntensity(), Reduction);
-			return false;
-		}
-	);
+	cSplashPotionCallback Callback(a_HitPos, m_EntityEffectType, m_EntityEffect);
+	m_World->ForEachEntity(Callback);
 
 	m_World->BroadcastSoundParticleEffect(
 		EffectID::PARTICLE_SPLASH_POTION,
diff --git a/src/Entities/ThrownEnderPearlEntity.cpp b/src/Entities/ThrownEnderPearlEntity.cpp
index cb0b3ada0..4b2e2f9ff 100644
--- a/src/Entities/ThrownEnderPearlEntity.cpp
+++ b/src/Entities/ThrownEnderPearlEntity.cpp
@@ -74,12 +74,29 @@ void cThrownEnderPearlEntity::TeleportCreator(const Vector3d & a_HitPos)
 		return;
 	}
 
-	GetWorld()->FindAndDoWithPlayer(m_CreatorData.m_Name, [=](cPlayer & a_Entity)
+	class cProjectileCreatorCallbackForPlayers : public cPlayerListCallback
+	{
+	public:
+		cProjectileCreatorCallbackForPlayers(cEntity * a_Attacker, Vector3i a_CallbackHitPos) :
+			m_Attacker(a_Attacker),
+			m_HitPos(a_CallbackHitPos)
+		{
+		}
+
+		virtual bool Item(cPlayer * a_Entity) override
 		{
 			// Teleport the creator here, make them take 5 damage:
-			a_Entity.TeleportToCoords(a_HitPos.x, a_HitPos.y + 0.2, a_HitPos.z);
-			a_Entity.TakeDamage(dtEnderPearl, this, 5, 0);
+			a_Entity->TeleportToCoords(m_HitPos.x, m_HitPos.y + 0.2, m_HitPos.z);
+			a_Entity->TakeDamage(dtEnderPearl, m_Attacker, 5, 0);
 			return true;
 		}
-	);
+
+	private:
+
+		cEntity * m_Attacker;
+		Vector3i m_HitPos;
+	};
+
+	cProjectileCreatorCallbackForPlayers PCCFP(this, a_HitPos);
+	GetWorld()->FindAndDoWithPlayer(m_CreatorData.m_Name, PCCFP);
 }
diff --git a/src/Globals.h b/src/Globals.h
index 78c0539fb..0c48d2ad9 100644
--- a/src/Globals.h
+++ b/src/Globals.h
@@ -416,6 +416,20 @@ template class SizeChecker<UInt8,  1>;
 
 
 
+
+/** A generic interface used mainly in ForEach() functions */
+template <typename Type> class cItemCallback
+{
+public:
+	virtual ~cItemCallback() {}
+
+	/** Called for each item in the internal list; return true to stop the loop, or false to continue enumerating */
+	virtual bool Item(Type * a_Type) = 0;
+} ;
+
+
+
+
 /** Clamp X to the specified range. */
 template <typename T>
 T Clamp(T a_Value, T a_Min, T a_Max)
diff --git a/src/Items/ItemFishingRod.h b/src/Items/ItemFishingRod.h
index 0720cb3e1..012f13a6c 100644
--- a/src/Items/ItemFishingRod.h
+++ b/src/Items/ItemFishingRod.h
@@ -20,7 +20,8 @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // cFloaterCallback
-class cFloaterCallback
+class cFloaterCallback :
+	public cEntityCallback
 {
 public:
 	cFloaterCallback(void) :
@@ -29,14 +30,13 @@ public:
 	{
 	}
 
-	bool operator () (cEntity & a_Entity)
+	virtual bool Item(cEntity * a_Entity) override
 	{
-		auto & Floater = static_cast<cFloater &>(a_Entity);
-		m_CanPickup = Floater.CanPickup();
-		m_Pos = Floater.GetPosition();
-		m_BitePos = Floater.GetBitePos();
-		m_AttachedMobID = Floater.GetAttachedMobID();
-		Floater.Destroy(true);
+		m_CanPickup = reinterpret_cast<cFloater *>(a_Entity)->CanPickup();
+		m_Pos = Vector3d(a_Entity->GetPosX(), a_Entity->GetPosY(), a_Entity->GetPosZ());
+		m_BitePos = reinterpret_cast<cFloater *>(a_Entity)->GetBitePos();
+		m_AttachedMobID = reinterpret_cast<cFloater *>(a_Entity)->GetAttachedMobID();
+		a_Entity->Destroy(true);
 		return true;
 	}
 
@@ -57,6 +57,33 @@ protected:
 
 
 
+////////////////////////////////////////////////////////////////////////////////
+// cSweepEntityCallback:
+
+class cSweepEntityCallback :
+	public cEntityCallback
+{
+public:
+	cSweepEntityCallback(Vector3d a_PlayerPos) :
+		m_PlayerPos(a_PlayerPos)
+	{
+	}
+
+	virtual bool Item(cEntity * a_Entity) override
+	{
+		Vector3d Speed = m_PlayerPos - a_Entity->GetPosition();
+		a_Entity->AddSpeed(Speed);
+		return true;
+	}
+
+protected:
+	Vector3d m_PlayerPos;
+} ;
+
+
+
+
+
 class cItemFishingRodHandler :
 	public cItemHandler
 {
@@ -90,13 +117,8 @@ public:
 
 			if (FloaterInfo.IsAttached())
 			{
-				a_World->DoWithEntityByID(FloaterInfo.GetAttachedMobID(), [=](cEntity & a_Entity)
-					{
-						Vector3d Speed = a_Player->GetPosition() - a_Entity.GetPosition();
-						a_Entity.AddSpeed(Speed);
-						return true;
-					}
-				);
+				cSweepEntityCallback SweepEntity(a_Player->GetPosition());
+				a_World->DoWithEntityByID(FloaterInfo.GetAttachedMobID(), SweepEntity);
 			}
 			else if (FloaterInfo.CanPickup())
 			{
diff --git a/src/Items/ItemMobHead.h b/src/Items/ItemMobHead.h
index 5cbcf52f7..fdecabbbf 100644
--- a/src/Items/ItemMobHead.h
+++ b/src/Items/ItemMobHead.h
@@ -62,30 +62,42 @@ public:
 		int a_BlockX, int a_BlockY, int a_BlockZ, eBlockFace a_BlockFace
 	)
 	{
-		auto HeadType = static_cast<eMobHeadType>(a_EquippedItem.m_ItemDamage);
-		auto BlockMeta = static_cast<NIBBLETYPE>(a_BlockFace);
-
 		// Use a callback to set the properties of the mob head block entity:
-		a_World.DoWithBlockEntityAt(a_BlockX, a_BlockY, a_BlockZ, [&](cBlockEntity & a_BlockEntity)
+		class cCallback : public cBlockEntityCallback
+		{
+			cPlayer & m_Player;
+			eMobHeadType m_HeadType;
+			NIBBLETYPE m_BlockMeta;
+
+			virtual bool Item(cBlockEntity * a_BlockEntity)
 			{
-				if (a_BlockEntity.GetBlockType() != E_BLOCK_HEAD)
+				if (a_BlockEntity->GetBlockType() != E_BLOCK_HEAD)
 				{
 					return false;
 				}
-				auto & MobHeadEntity = static_cast<cMobHeadEntity &>(a_BlockEntity);
+				auto MobHeadEntity = static_cast<cMobHeadEntity *>(a_BlockEntity);
 
 				int Rotation = 0;
-				if (BlockMeta == 1)
+				if (m_BlockMeta == 1)
 				{
-					Rotation = FloorC(a_Player.GetYaw() * 16.0f / 360.0f + 0.5f) & 0x0f;
+					Rotation = FloorC(m_Player.GetYaw() * 16.0f / 360.0f + 0.5f) & 0x0f;
 				}
 
-				MobHeadEntity.SetType(HeadType);
-				MobHeadEntity.SetRotation(static_cast<eMobHeadRotation>(Rotation));
-				MobHeadEntity.GetWorld()->BroadcastBlockEntity(MobHeadEntity.GetPosX(), MobHeadEntity.GetPosY(), MobHeadEntity.GetPosZ());
+				MobHeadEntity->SetType(m_HeadType);
+				MobHeadEntity->SetRotation(static_cast<eMobHeadRotation>(Rotation));
+				MobHeadEntity->GetWorld()->BroadcastBlockEntity(MobHeadEntity->GetPosX(), MobHeadEntity->GetPosY(), MobHeadEntity->GetPosZ());
 				return false;
 			}
-		);
+
+		public:
+			cCallback (cPlayer & a_CBPlayer, eMobHeadType a_HeadType, NIBBLETYPE a_BlockMeta) :
+				m_Player(a_CBPlayer),
+				m_HeadType(a_HeadType),
+				m_BlockMeta(a_BlockMeta)
+			{}
+		};
+		cCallback Callback(a_Player, static_cast<eMobHeadType>(a_EquippedItem.m_ItemDamage), static_cast<NIBBLETYPE>(a_BlockFace));
+		a_World.DoWithBlockEntityAt(a_BlockX, a_BlockY, a_BlockZ, Callback);
 	}
 
 
@@ -231,16 +243,24 @@ public:
 			// If it is a mob head, check the correct head type using the block entity:
 			if (BlockType == E_BLOCK_HEAD)
 			{
-				bool IsWitherHead = false;
-				a_World.DoWithBlockEntityAt(BlockX, BlockY, BlockZ, [&](cBlockEntity & a_Entity)
+				class cHeadCallback: public cBlockEntityCallback
+				{
+					virtual bool Item(cBlockEntity * a_Entity) override
 					{
-						ASSERT(a_Entity.GetBlockType() == E_BLOCK_HEAD);
-						auto & MobHead = static_cast<cMobHeadEntity &>(a_Entity);
-						IsWitherHead = (MobHead.GetType() == SKULL_TYPE_WITHER);
+						ASSERT(a_Entity->GetBlockType() == E_BLOCK_HEAD);
+						cMobHeadEntity * MobHead = static_cast<cMobHeadEntity *>(a_Entity);
+						m_IsWitherHead = (MobHead->GetType() == SKULL_TYPE_WITHER);
 						return true;
 					}
-				);
-				if (!IsWitherHead)
+				public:
+					cHeadCallback(void):
+						m_IsWitherHead(false)
+					{
+					}
+					bool m_IsWitherHead;
+				} callback;
+				a_World.DoWithBlockEntityAt(BlockX, BlockY, BlockZ, callback);
+				if (!callback.m_IsWitherHead)
 				{
 					return false;
 				}
@@ -267,18 +287,25 @@ public:
 	/** Awards the achievement to all players close to the specified point. */
 	void AwardSpawnWitherAchievement(cWorld & a_World, int a_BlockX, int a_BlockY, int a_BlockZ)
 	{
-		Vector3f Pos{ static_cast<float>(a_BlockX), static_cast<float>(a_BlockY), static_cast<float>(a_BlockZ) };
-		a_World.ForEachPlayer([=](cPlayer & a_Player)
+		class cPlayerCallback : public cPlayerListCallback
+		{
+			Vector3f m_Pos;
+
+			virtual bool Item(cPlayer * a_Player)
 			{
 				// If player is close, award achievement:
-				double Dist = (a_Player.GetPosition() - Pos).Length();
+				double Dist = (a_Player->GetPosition() - m_Pos).Length();
 				if (Dist < 50.0)
 				{
-					a_Player.AwardAchievement(achSpawnWither);
+					a_Player->AwardAchievement(achSpawnWither);
 				}
 				return false;
 			}
-		);
+
+		public:
+			cPlayerCallback(const Vector3f & a_Pos) : m_Pos(a_Pos) {}
+		} PlayerCallback(Vector3f(static_cast<float>(a_BlockX), static_cast<float>(a_BlockY), static_cast<float>(a_BlockZ)));
+		a_World.ForEachPlayer(PlayerCallback);
 	}
 
 
diff --git a/src/LineBlockTracer.cpp b/src/LineBlockTracer.cpp
index e194ae653..471d9e13b 100644
--- a/src/LineBlockTracer.cpp
+++ b/src/LineBlockTracer.cpp
@@ -199,12 +199,12 @@ bool cLineBlockTracer::Trace(double a_StartX, double a_StartY, double a_StartZ,
 	m_DiffY = m_EndY - m_StartY;
 	m_DiffZ = m_EndZ - m_StartZ;
 
-	// The actual trace is handled with ChunkMapCS locked by calling our ChunkCallback for the specified chunk
+	// The actual trace is handled with ChunkMapCS locked by calling our Item() for the specified chunk
 	int BlockX = FloorC(m_StartX);
 	int BlockZ = FloorC(m_StartZ);
 	int ChunkX, ChunkZ;
 	cChunkDef::BlockToChunk(BlockX, BlockZ, ChunkX, ChunkZ);
-	return m_World->DoWithChunk(ChunkX, ChunkZ, [this](cChunk & a_Chunk) { return ChunkCallback(&a_Chunk); });
+	return m_World->DoWithChunk(ChunkX, ChunkZ, *this);
 }
 
 
@@ -308,7 +308,7 @@ bool cLineBlockTracer::MoveToNextBlock(void)
 
 
 
-bool cLineBlockTracer::ChunkCallback(cChunk * a_Chunk)
+bool cLineBlockTracer::Item(cChunk * a_Chunk)
 {
 	ASSERT((m_CurrentY >= 0) && (m_CurrentY < cChunkDef::Height));  // This should be provided by FixStartAboveWorld() / FixStartBelowWorld()
 
diff --git a/src/LineBlockTracer.h b/src/LineBlockTracer.h
index 2204e3671..2851cfbd7 100644
--- a/src/LineBlockTracer.h
+++ b/src/LineBlockTracer.h
@@ -18,12 +18,17 @@
 // fwd: Chunk.h
 class cChunk;
 
+// fwd: cChunkMap.h
+typedef cItemCallback<cChunk> cChunkCallback;
+
+
 
 
 
 
 class cLineBlockTracer :
-	public cBlockTracer
+	public cBlockTracer,
+	public cChunkCallback
 {
 	typedef cBlockTracer super;
 
@@ -104,7 +109,8 @@ protected:
 	/** Moves m_Current to the next block on the line; returns false if no move is possible (reached the end) */
 	bool MoveToNextBlock(void);
 
-	bool ChunkCallback(cChunk * a_Chunk);
+	// cChunkCallback overrides:
+	virtual bool Item(cChunk * a_Chunk) override;
 } ;
 
 
diff --git a/src/Map.cpp b/src/Map.cpp
index 87cc9bfdf..2fe901d8e 100644
--- a/src/Map.cpp
+++ b/src/Map.cpp
@@ -120,17 +120,27 @@ bool cMap::UpdatePixel(unsigned int a_X, unsigned int a_Z)
 	int RelX = BlockX - (ChunkX * cChunkDef::Width);
 	int RelZ = BlockZ - (ChunkZ * cChunkDef::Width);
 
-	ASSERT(m_World != nullptr);
+	class cCalculatePixelCb :
+		public cChunkCallback
+	{
+		cMap * m_Map;
+
+		int m_RelX, m_RelZ;
+
+		ColorID m_PixelData;
+
+	public:
+		cCalculatePixelCb(cMap * a_Map, int a_RelX, int a_RelZ)
+			: m_Map(a_Map), m_RelX(a_RelX), m_RelZ(a_RelZ), m_PixelData(E_BASE_COLOR_TRANSPARENT) {}
 
-	ColorID PixelData;
-	m_World->DoWithChunk(ChunkX, ChunkZ, [&](cChunk & a_Chunk)
+		virtual bool Item(cChunk * a_Chunk) override
 		{
-			if (!a_Chunk.IsValid())
+			if (!a_Chunk->IsValid())
 			{
 				return false;
 			}
 
-			if (GetDimension() == dimNether)
+			if (m_Map->GetDimension() == dimNether)
 			{
 				// TODO 2014-02-22 xdot: Nether maps
 
@@ -141,22 +151,22 @@ bool cMap::UpdatePixel(unsigned int a_X, unsigned int a_Z)
 			BLOCKTYPE TargetBlock;
 			NIBBLETYPE TargetMeta;
 
-			auto Height = a_Chunk.GetHeight(RelX, RelZ);
+			auto Height = a_Chunk->GetHeight(m_RelX, m_RelZ);
 			auto ChunkHeight = cChunkDef::Height;
-			a_Chunk.GetBlockTypeMeta(RelX, Height, RelZ, TargetBlock, TargetMeta);
+			a_Chunk->GetBlockTypeMeta(m_RelX, Height, m_RelZ, TargetBlock, TargetMeta);
 			auto ColourID = BlockHandler(TargetBlock)->GetMapBaseColourID(TargetMeta);
 
 			if (IsBlockWater(TargetBlock))
 			{
 				ChunkHeight /= 4;
-				while (((--Height) != -1) && IsBlockWater(a_Chunk.GetBlock(RelX, Height, RelZ)))
+				while (((--Height) != -1) && IsBlockWater(a_Chunk->GetBlock(m_RelX, Height, m_RelZ)))
 				{
 					continue;
 				}
 			}
 			else if (ColourID == 0)
 			{
-				while (((--Height) != -1) && ((ColourID = BlockHandler(a_Chunk.GetBlock(RelX, Height, RelZ))->GetMapBaseColourID(a_Chunk.GetMeta(RelX, Height, RelZ))) == 0))
+				while (((--Height) != -1) && ((ColourID = BlockHandler(a_Chunk->GetBlock(m_RelX, Height, m_RelZ))->GetMapBaseColourID(a_Chunk->GetMeta(m_RelX, Height, m_RelZ))) == 0))
 				{
 					continue;
 				}
@@ -164,12 +174,20 @@ bool cMap::UpdatePixel(unsigned int a_X, unsigned int a_Z)
 
 			// Multiply base color ID by 4 and add brightness ID
 			const int BrightnessIDSize = static_cast<int>(BrightnessID.size());
-			PixelData = ColourID * 4 + BrightnessID[static_cast<size_t>(Clamp<int>((BrightnessIDSize * Height) / ChunkHeight, 0, BrightnessIDSize - 1))];
+			m_PixelData = ColourID * 4 + BrightnessID[static_cast<size_t>(Clamp<int>((BrightnessIDSize * Height) / ChunkHeight, 0, BrightnessIDSize - 1))];
 			return false;
 		}
-	);
 
-	SetPixel(a_X, a_Z, PixelData);
+		ColorID GetPixelData(void) const
+		{
+			return m_PixelData;
+		}
+	} CalculatePixelCb(this, RelX, RelZ);
+
+	ASSERT(m_World != nullptr);
+	m_World->DoWithChunk(ChunkX, ChunkZ, CalculatePixelCb);
+
+	SetPixel(a_X, a_Z, CalculatePixelCb.GetPixelData());
 
 	return true;
 }
diff --git a/src/MapManager.cpp b/src/MapManager.cpp
index abc3f16f2..2729e67dd 100644
--- a/src/MapManager.cpp
+++ b/src/MapManager.cpp
@@ -1,4 +1,4 @@
-
+
 // MapManager.cpp
 
 #include "Globals.h"
@@ -22,7 +22,7 @@ cMapManager::cMapManager(cWorld * a_World)
 
 
 
-bool cMapManager::DoWithMap(UInt32 a_ID, const cMapCallback & a_Callback)
+bool cMapManager::DoWithMap(UInt32 a_ID, cMapCallback & a_Callback)
 {
 	cCSLock Lock(m_CS);
 	cMap * Map = GetMapData(a_ID);
@@ -33,7 +33,7 @@ bool cMapManager::DoWithMap(UInt32 a_ID, const cMapCallback & a_Callback)
 	}
 	else
 	{
-		a_Callback(*Map);
+		a_Callback.Item(Map);
 		return true;
 	}
 }
diff --git a/src/MapManager.h b/src/MapManager.h
index ef1e7588b..6730e515e 100644
--- a/src/MapManager.h
+++ b/src/MapManager.h
@@ -1,4 +1,4 @@
-
+
 // MapManager.h
 
 
@@ -11,13 +11,12 @@
 
 
 
-#include <functional>
 #include "Map.h"
 
 
 
 
-using cMapCallback = std::function<bool(cMap &)>;
+typedef cItemCallback<cMap> cMapCallback;
 
 
 
@@ -42,7 +41,7 @@ public:
 	/** Calls the callback for the map with the specified ID.
 	Returns true if the map was found and the callback called, false if map not found.
 	Callback return value is ignored. */
-	bool DoWithMap(UInt32 a_ID, const cMapCallback & a_Callback);  // Exported in ManualBindings.cpp
+	bool DoWithMap(UInt32 a_ID, cMapCallback & a_Callback);  // Exported in ManualBindings.cpp
 
 	/** Ticks each registered map */
 	void TickMaps(void);
diff --git a/src/MobSpawner.cpp b/src/MobSpawner.cpp
index eb5684202..1e0db5175 100644
--- a/src/MobSpawner.cpp
+++ b/src/MobSpawner.cpp
@@ -369,7 +369,7 @@ cMonster * cMobSpawner::TryToSpawnHere(cChunk * a_Chunk, int a_RelX, int a_RelY,
 		auto NewMobPtr = newMob.get();
 		if (newMob)
 		{
-			m_Spawned.push_back(std::move(newMob));
+			m_Spawned.insert(std::move(newMob));
 		}
 		return NewMobPtr;
 	}
@@ -390,6 +390,15 @@ void cMobSpawner::NewPack()
 
 
 
+cMobSpawner::tSpawnedContainer & cMobSpawner::getSpawned(void)
+{
+	return m_Spawned;
+}
+
+
+
+
+
 bool cMobSpawner::CanSpawnAnything(void)
 {
 	return !m_AllowedTypes.empty();
diff --git a/src/MobSpawner.h b/src/MobSpawner.h
index c396637d5..14c721ae3 100644
--- a/src/MobSpawner.h
+++ b/src/MobSpawner.h
@@ -37,10 +37,8 @@ public :
 	// return true if there is at least one allowed type
 	bool CanSpawnAnything(void);
 
-	std::vector<std::unique_ptr<cMonster>> & getSpawned(void)
-	{
-		return m_Spawned;
-	}
+	typedef const std::set<std::unique_ptr<cMonster>> tSpawnedContainer;
+	tSpawnedContainer & getSpawned(void);
 
 	/** Returns true if specified type of mob can spawn on specified block */
 	static bool CanSpawnHere(cChunk * a_Chunk, int a_RelX, int a_RelY, int a_RelZ, eMonsterType a_MobType, EMCSBiome a_Biome);
@@ -57,7 +55,7 @@ protected :
 	std::set<eMonsterType> m_AllowedTypes;
 	bool m_NewPack;
 	eMonsterType m_MobType;
-	std::vector<std::unique_ptr<cMonster>> m_Spawned;
+	std::set<std::unique_ptr<cMonster>> m_Spawned;
 } ;
 
 
diff --git a/src/Mobs/Creeper.cpp b/src/Mobs/Creeper.cpp
index 3c43cc523..8996db38e 100644
--- a/src/Mobs/Creeper.cpp
+++ b/src/Mobs/Creeper.cpp
@@ -46,16 +46,21 @@ void cCreeper::GetDrops(cItems & a_Drops, cEntity * a_Killer)
 		a_Killer->IsProjectile() &&
 		((reinterpret_cast<cProjectileEntity *>(a_Killer))->GetCreatorUniqueID() != cEntity::INVALID_ID))
 	{
-		auto ProjectileCreatorCallback = [](cEntity & a_Entity)
+		class cProjectileCreatorCallback : public cEntityCallback
+		{
+		public:
+			cProjectileCreatorCallback(void) {}
+
+			virtual bool Item(cEntity * a_Entity) override
 			{
-				if (a_Entity.IsMob() && ((static_cast<cMonster &>(a_Entity)).GetMobType() == mtSkeleton))
+				if (a_Entity->IsMob() && ((reinterpret_cast<cMonster *>(a_Entity))->GetMobType() == mtSkeleton))
 				{
 					return true;
 				}
 				return false;
-			};
-
-		if (GetWorld()->DoWithEntityByID(static_cast<cProjectileEntity *>(a_Killer)->GetCreatorUniqueID(), ProjectileCreatorCallback))
+			}
+		} PCC;
+		if (GetWorld()->DoWithEntityByID((reinterpret_cast<cProjectileEntity *>(a_Killer))->GetCreatorUniqueID(), PCC))
 		{
 			AddRandomDropItem(a_Drops, 1, 1, static_cast<short>(m_World->GetTickRandomNumber(11) + E_ITEM_FIRST_DISC));
 		}
diff --git a/src/Mobs/Enderman.cpp b/src/Mobs/Enderman.cpp
index be9329d06..3d874e4d6 100644
--- a/src/Mobs/Enderman.cpp
+++ b/src/Mobs/Enderman.cpp
@@ -10,7 +10,8 @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // cPlayerLookCheck
-class cPlayerLookCheck
+class cPlayerLookCheck :
+	public cPlayerListCallback
 {
 public:
 	cPlayerLookCheck(Vector3d a_EndermanPos, int a_SightDistance) :
@@ -20,29 +21,29 @@ public:
 	{
 	}
 
-	bool operator () (cPlayer & a_Player)
+	virtual bool Item(cPlayer * a_Player) override
 	{
 		// Don't check players who cannot be targeted
-		if (!a_Player.CanMobsTarget())
+		if (!a_Player->CanMobsTarget())
 		{
 			return false;
 		}
 
 		// Don't check players who are more than SightDistance (64) blocks away
-		auto Direction = m_EndermanPos - a_Player.GetPosition();
+		auto Direction = m_EndermanPos - a_Player->GetPosition();
 		if (Direction.Length() > m_SightDistance)
 		{
 			return false;
 		}
 
 		// Don't check if the player has a pumpkin on his head
-		if (a_Player.GetEquippedHelmet().m_ItemType == E_BLOCK_PUMPKIN)
+		if (a_Player->GetEquippedHelmet().m_ItemType == E_BLOCK_PUMPKIN)
 		{
 			return false;
 		}
 
 		// If the player's crosshair is within 5 degrees of the enderman, it counts as looking
-		auto LookVector = a_Player.GetLookVector();
+		auto LookVector = a_Player->GetLookVector();
 		auto dot = Direction.Dot(LookVector);
 		if (dot <= cos(0.09))  // 0.09 rad ~ 5 degrees
 		{
@@ -50,13 +51,13 @@ public:
 		}
 
 		// TODO: Check if endermen are angered through water in Vanilla
-		if (!cLineBlockTracer::LineOfSightTrace(*a_Player.GetWorld(), m_EndermanPos, a_Player.GetPosition(), cLineBlockTracer::losAirWater))
+		if (!cLineBlockTracer::LineOfSightTrace(*a_Player->GetWorld(), m_EndermanPos, a_Player->GetPosition(), cLineBlockTracer::losAirWater))
 		{
 			// No direct line of sight
 			return false;
 		}
 
-		m_Player = &a_Player;
+		m_Player = a_Player;
 		return true;
 	}
 
diff --git a/src/Mobs/Ocelot.cpp b/src/Mobs/Ocelot.cpp
index 35a805994..de776dac6 100644
--- a/src/Mobs/Ocelot.cpp
+++ b/src/Mobs/Ocelot.cpp
@@ -92,25 +92,30 @@ void cOcelot::Tick(std::chrono::milliseconds a_Dt, cChunk & a_Chunk)
 
 void cOcelot::TickFollowPlayer()
 {
-	Vector3d OwnerPos;
-	bool OwnerFlying = false;
-	auto Callback = [&](cPlayer & a_Player)
+	class cCallback :
+		public cPlayerListCallback
 	{
-		OwnerPos = a_Player.GetPosition();
-		OwnerFlying = a_Player.IsFlying();
-		return true;
-	};
+		virtual bool Item(cPlayer * a_Player) override
+		{
+			OwnerPos = a_Player->GetPosition();
+			OwnerFlying = a_Player->IsFlying();
+			return true;
+		}
+	public:
+		Vector3d OwnerPos;
+		bool OwnerFlying;
+	} Callback;
 
 	if (m_World->DoWithPlayerByUUID(m_OwnerUUID, Callback))
 	{
 		// The player is present in the world, follow him:
-		double Distance = (OwnerPos - GetPosition()).Length();
+		double Distance = (Callback.OwnerPos - GetPosition()).Length();
 		if (Distance > 12)
 		{
-			if (!OwnerFlying)
+			if (!Callback.OwnerFlying)
 			{
-				OwnerPos.y = FindFirstNonAirBlockPosition(OwnerPos.x, OwnerPos.z);
-				TeleportToCoords(OwnerPos.x, OwnerPos.y, OwnerPos.z);
+				Callback.OwnerPos.y = FindFirstNonAirBlockPosition(Callback.OwnerPos.x, Callback.OwnerPos.z);
+				TeleportToCoords(Callback.OwnerPos.x, Callback.OwnerPos.y, Callback.OwnerPos.z);
 			}
 		}
 		if (Distance < 2)
@@ -119,9 +124,9 @@ void cOcelot::TickFollowPlayer()
 		}
 		else
 		{
-			if (!OwnerFlying)
+			if (!Callback.OwnerFlying)
 			{
-				MoveToPosition(OwnerPos);
+				MoveToPosition(Callback.OwnerPos);
 			}
 		}
 	}
@@ -202,19 +207,27 @@ void cOcelot::SpawnOn(cClientHandle & a_ClientHandle)
 
 
 
+class cFindSittingCat :
+	public cEntityCallback
+{
+	virtual bool Item(cEntity * a_Entity) override
+	{
+		return (
+			(a_Entity->GetEntityType() == cEntity::etMonster) &&
+			(static_cast<cMonster *>(a_Entity)->GetMobType() == eMonsterType::mtOcelot) &&
+			(static_cast<cOcelot *>(a_Entity)->IsSitting())
+		);
+	}
+};
+
+
+
+
+
 bool cOcelot::IsCatSittingOnBlock(cWorld * a_World, Vector3d a_BlockPosition)
 {
-	return a_World->ForEachEntityInBox(
-		cBoundingBox(Vector3d(a_BlockPosition.x, a_BlockPosition.y + 1, a_BlockPosition.z), 1),
-		[=](cEntity & a_Entity)
-		{
-			return (
-				(a_Entity.GetEntityType() == cEntity::etMonster) &&
-				(static_cast<cMonster &>(a_Entity).GetMobType() == eMonsterType::mtOcelot) &&
-				(static_cast<cOcelot &>(a_Entity).IsSitting())
-			);
-		}
-	);
+	cFindSittingCat FindSittingCat;
+	return a_World->ForEachEntityInBox(cBoundingBox(Vector3d(a_BlockPosition.x, a_BlockPosition.y + 1, a_BlockPosition.z), 1), FindSittingCat);
 }
 
 
diff --git a/src/Mobs/PassiveMonster.cpp b/src/Mobs/PassiveMonster.cpp
index c9345662d..a2089e13f 100644
--- a/src/Mobs/PassiveMonster.cpp
+++ b/src/Mobs/PassiveMonster.cpp
@@ -109,18 +109,23 @@ void cPassiveMonster::Tick(std::chrono::milliseconds a_Dt, cChunk & a_Chunk)
 			Vector3f Pos = (GetPosition() + m_LovePartner->GetPosition()) * 0.5;
 			UInt32 BabyID = m_World->SpawnMob(Pos.x, Pos.y, Pos.z, GetMobType(), true);
 
-			cPassiveMonster * Baby = nullptr;
-
-			m_World->DoWithEntityByID(BabyID, [&](cEntity & a_Entity)
+			class cBabyInheritCallback :
+				public cEntityCallback
+			{
+			public:
+				cPassiveMonster * Baby;
+				cBabyInheritCallback() : Baby(nullptr) { }
+				virtual bool Item(cEntity * a_Entity) override
 				{
-					Baby = static_cast<cPassiveMonster *>(&a_Entity);
+					Baby = static_cast<cPassiveMonster *>(a_Entity);
 					return true;
 				}
-			);
+			} Callback;
 
-			if (Baby != nullptr)
+			m_World->DoWithEntityByID(BabyID, Callback);
+			if (Callback.Baby != nullptr)
 			{
-				Baby->InheritFromParents(this, m_LovePartner);
+				Callback.Baby->InheritFromParents(this, m_LovePartner);
 			}
 
 			m_World->SpawnExperienceOrb(Pos.x, Pos.y, Pos.z, GetRandomProvider().RandInt(1, 6));
@@ -154,37 +159,49 @@ void cPassiveMonster::Tick(std::chrono::milliseconds a_Dt, cChunk & a_Chunk)
 	{
 		if (m_LovePartner == nullptr)
 		{
-			m_World->ForEachEntityInBox(cBoundingBox(GetPosition(), 8, 8), [=](cEntity & a_Entity)
+			class LookForLover : public cEntityCallback
+			{
+			public:
+				cEntity * m_Me;
+
+				LookForLover(cEntity * a_Me) :
+					m_Me(a_Me)
+				{
+				}
+
+				virtual bool Item(cEntity * a_Entity) override
 				{
 					// If the entity is not a monster, don't breed with it
 					// Also, do not self-breed
-					if ((a_Entity.GetEntityType() != etMonster) || (&a_Entity == this))
+					if ((a_Entity->GetEntityType() != etMonster) || (a_Entity == m_Me))
 					{
 						return false;
 					}
 
-					auto & Me = static_cast<cPassiveMonster&>(*this);
-					auto & PotentialPartner = static_cast<cPassiveMonster&>(a_Entity);
+					cPassiveMonster * Me = static_cast<cPassiveMonster*>(m_Me);
+					cPassiveMonster * PotentialPartner = static_cast<cPassiveMonster*>(a_Entity);
 
 					// If the potential partner is not of the same species, don't breed with it
-					if (PotentialPartner.GetMobType() != Me.GetMobType())
+					if (PotentialPartner->GetMobType() != Me->GetMobType())
 					{
 						return false;
 					}
 
 					// If the potential partner is not in love
 					// Or they already have a mate, do not breed with them
-					if ((!PotentialPartner.IsInLove()) || (PotentialPartner.GetPartner() != nullptr))
+					if ((!PotentialPartner->IsInLove()) || (PotentialPartner->GetPartner() != nullptr))
 					{
 						return false;
 					}
 
 					// All conditions met, let's breed!
-					PotentialPartner.EngageLoveMode(&Me);
-					Me.EngageLoveMode(&PotentialPartner);
+					PotentialPartner->EngageLoveMode(Me);
+					Me->EngageLoveMode(PotentialPartner);
 					return true;
 				}
-			);
+			} Callback(this);
+
+			m_World->ForEachEntityInBox(cBoundingBox(GetPosition(), 8, 8, -4), Callback);
 		}
 
 		m_LoveTimer--;
diff --git a/src/Mobs/Wither.cpp b/src/Mobs/Wither.cpp
index adb7305df..e58d47426 100644
--- a/src/Mobs/Wither.cpp
+++ b/src/Mobs/Wither.cpp
@@ -103,19 +103,28 @@ void cWither::KilledBy(TakeDamageInfo & a_TDI)
 {
 	super::KilledBy(a_TDI);
 
-	Vector3d Pos = GetPosition();
-	m_World->ForEachPlayer([=](cPlayer & a_Player)
+	class cPlayerCallback : public cPlayerListCallback
+	{
+		Vector3f m_Pos;
+
+		virtual bool Item(cPlayer * a_Player)
 		{
 			// TODO 2014-05-21 xdot: Vanilla minecraft uses an AABB check instead of a radius one
-			double Dist = (a_Player.GetPosition() - Pos).Length();
+			double Dist = (a_Player->GetPosition() - m_Pos).Length();
 			if (Dist < 50.0)
 			{
 				// If player is close, award achievement
-				a_Player.AwardAchievement(achKillWither);
+				a_Player->AwardAchievement(achKillWither);
 			}
 			return false;
 		}
-	);
+
+	public:
+		cPlayerCallback(const Vector3f & a_Pos) : m_Pos(a_Pos) {}
+
+	} PlayerCallback(GetPosition());
+
+	m_World->ForEachPlayer(PlayerCallback);
 }
 
 
diff --git a/src/Mobs/Wolf.cpp b/src/Mobs/Wolf.cpp
index bf49c70f8..bfc7b10e8 100644
--- a/src/Mobs/Wolf.cpp
+++ b/src/Mobs/Wolf.cpp
@@ -29,7 +29,6 @@ cWolf::cWolf(void) :
 
 
 
-
 bool cWolf::DoTakeDamage(TakeDamageInfo & a_TDI)
 {
 	/*TODO bring from master and adapt*/
diff --git a/src/Root.cpp b/src/Root.cpp
index f773ab06e..3e30d8a07 100644
--- a/src/Root.cpp
+++ b/src/Root.cpp
@@ -1,4 +1,4 @@
-
+
 #include "Globals.h"  // NOTE: MSVC stupidness requires this to be the same across all modules
 
 #include "Root.h"
@@ -352,16 +352,22 @@ void cRoot::Start(std::unique_ptr<cSettingsRepositoryInterface> a_OverridesRepo)
 void cRoot::StopServer()
 {
 	// Kick all players from the server with custom disconnect message
-
-	bool SentDisconnect = false;
-	cRoot::Get()->ForEachPlayer([&](cPlayer & a_Player)
+	class cPlayerCallback : public cPlayerListCallback
+	{
+		AString m_ShutdownMessage;
+		virtual bool Item(cPlayer * a_Player)
 		{
-			a_Player.GetClientHandlePtr()->Kick(m_Server->GetShutdownMessage());
-			SentDisconnect = true;
+			a_Player->GetClientHandlePtr()->Kick(m_ShutdownMessage);
+			m_HasSentDisconnect = true;
 			return false;
 		}
-	);
-	if (SentDisconnect)
+	public:
+		bool m_HasSentDisconnect;
+		cPlayerCallback(AString a_ShutdownMessage) : m_ShutdownMessage(a_ShutdownMessage) { m_HasSentDisconnect = false; }
+	} PlayerCallback(m_Server->GetShutdownMessage());
+
+	cRoot::Get()->ForEachPlayer(PlayerCallback);
+	if (PlayerCallback.m_HasSentDisconnect)
 	{
 		std::this_thread::sleep_for(std::chrono::seconds(1));
 	}
@@ -578,13 +584,14 @@ cWorld * cRoot::GetWorld(const AString & a_WorldName)
 
 
 
-bool cRoot::ForEachWorld(const cWorldListCallback & a_Callback)
+bool cRoot::ForEachWorld(cWorldListCallback & a_Callback)
 {
-	for (auto & World : m_WorldsByName)
+	for (WorldMap::iterator itr = m_WorldsByName.begin(), itr2 = itr; itr != m_WorldsByName.end(); itr = itr2)
 	{
-		if (World.second != nullptr)
+		++itr2;
+		if (itr->second != nullptr)
 		{
-			if (a_Callback(*World.second))
+			if (a_Callback.Item(itr->second))
 			{
 				return false;
 			}
@@ -743,7 +750,7 @@ void cRoot::BroadcastChat(const cCompositeChat & a_Message)
 
 
 
-bool cRoot::ForEachPlayer(const cPlayerListCallback & a_Callback)
+bool cRoot::ForEachPlayer(cPlayerListCallback & a_Callback)
 {
 	for (WorldMap::iterator itr = m_WorldsByName.begin(), itr2 = itr; itr != m_WorldsByName.end(); itr = itr2)
 	{
@@ -760,22 +767,20 @@ bool cRoot::ForEachPlayer(const cPlayerListCallback & a_Callback)
 
 
 
-bool cRoot::FindAndDoWithPlayer(const AString & a_PlayerName, const cPlayerListCallback & a_Callback)
+bool cRoot::FindAndDoWithPlayer(const AString & a_PlayerName, cPlayerListCallback & a_Callback)
 {
-	class cCallback
+	class cCallback : public cPlayerListCallback
 	{
 		size_t        m_BestRating;
 		size_t        m_NameLength;
 		const AString m_PlayerName;
 
-	public:
-
-		bool operator () (cPlayer & a_Player)
+		virtual bool Item (cPlayer * a_pPlayer)
 		{
-			size_t Rating = RateCompareString (m_PlayerName, a_Player.GetName());
+			size_t Rating = RateCompareString (m_PlayerName, a_pPlayer->GetName());
 			if ((Rating > 0) && (Rating >= m_BestRating))
 			{
-				m_BestMatch = a_Player.GetName();
+				m_BestMatch = a_pPlayer->GetName();
 				if (Rating > m_BestRating)
 				{
 					m_NumMatches = 0;
@@ -790,6 +795,7 @@ bool cRoot::FindAndDoWithPlayer(const AString & a_PlayerName, const cPlayerListC
 			return false;
 		}
 
+	public:
 		cCallback (const AString & a_CBPlayerName) :
 			m_BestRating(0),
 			m_NameLength(a_CBPlayerName.length()),
@@ -814,7 +820,7 @@ bool cRoot::FindAndDoWithPlayer(const AString & a_PlayerName, const cPlayerListC
 
 
 
-bool cRoot::DoWithPlayerByUUID(const cUUID & a_PlayerUUID, const cPlayerListCallback & a_Callback)
+bool cRoot::DoWithPlayerByUUID(const cUUID & a_PlayerUUID, cPlayerListCallback & a_Callback)
 {
 	for (WorldMap::iterator itr = m_WorldsByName.begin(); itr !=  m_WorldsByName.end(); ++itr)
 	{
@@ -830,7 +836,7 @@ bool cRoot::DoWithPlayerByUUID(const cUUID & a_PlayerUUID, const cPlayerListCall
 
 
 
-bool cRoot::DoWithPlayer(const AString & a_PlayerName, const cPlayerListCallback & a_Callback)
+bool cRoot::DoWithPlayer(const AString & a_PlayerName, cPlayerListCallback & a_Callback)
 {
 	for (auto World : m_WorldsByName)
 	{
@@ -1022,11 +1028,25 @@ int cRoot::GetFurnaceFuelBurnTime(const cItem & a_Fuel)
 AStringVector cRoot::GetPlayerTabCompletionMultiWorld(const AString & a_Text)
 {
 	AStringVector Results;
-	ForEachWorld([&](cWorld & a_World)
+	class cWorldCallback : public cWorldListCallback
+	{
+	public:
+		cWorldCallback(AStringVector & a_Results, const AString & a_Search) :
+			m_Results(a_Results),
+			m_Search(a_Search)
 		{
-			a_World.TabCompleteUserName(a_Text, Results);
+		}
+
+		virtual bool Item(cWorld * a_World) override
+		{
+			a_World->TabCompleteUserName(m_Search, m_Results);
 			return false;
 		}
-	);
+	private:
+		AStringVector & m_Results;
+		const AString & m_Search;
+	} WC(Results, a_Text);
+
+	Get()->ForEachWorld(WC);
 	return Results;
 }
diff --git a/src/Root.h b/src/Root.h
index 09e2c7880..44567018d 100644
--- a/src/Root.h
+++ b/src/Root.h
@@ -1,11 +1,10 @@
-
+
 #pragma once
 
 #include "Protocol/Authenticator.h"
 #include "Protocol/MojangAPI.h"
 #include "HTTP/HTTPServer.h"
 #include "Defines.h"
-#include <functional>
 #include "RankManager.h"
 
 
@@ -28,8 +27,8 @@ class cSettingsRepositoryInterface;
 class cDeadlockDetect;
 class cUUID;
 
-using cPlayerListCallback =  std::function<bool(cPlayer &)>;
-using cWorldListCallback  =  std::function<bool(cWorld  &)>;
+typedef cItemCallback<cPlayer> cPlayerListCallback;
+typedef cItemCallback<cWorld>  cWorldListCallback;
 
 namespace Json
 {
@@ -77,7 +76,7 @@ public:
 	// tolua_end
 
 	/** Calls the callback for each world; returns true if the callback didn't abort (return true) */
-	bool ForEachWorld(const cWorldListCallback & a_Callback);  // >> Exported in ManualBindings <<
+	bool ForEachWorld(cWorldListCallback & a_Callback);  // >> Exported in ManualBindings <<
 
 	/** Writes chunkstats, for each world and totals, to the output callback */
 	void LogChunkStats(cCommandOutputCallback & a_Output);
@@ -137,16 +136,16 @@ public:
 	void SaveAllChunks(void);  // tolua_export
 
 	/** Calls the callback for each player in all worlds */
-	bool ForEachPlayer(const cPlayerListCallback & a_Callback);  // >> EXPORTED IN MANUALBINDINGS <<
+	bool ForEachPlayer(cPlayerListCallback & a_Callback);  // >> EXPORTED IN MANUALBINDINGS <<
 
 	/** Finds a player from a partial or complete player name and calls the callback - case-insensitive */
-	bool FindAndDoWithPlayer(const AString & a_PlayerName, const cPlayerListCallback & a_Callback);  // >> EXPORTED IN MANUALBINDINGS <<
+	bool FindAndDoWithPlayer(const AString & a_PlayerName, cPlayerListCallback & a_Callback);  // >> EXPORTED IN MANUALBINDINGS <<
 
 	/** Finds the player over his uuid and calls the callback */
-	bool DoWithPlayerByUUID(const cUUID & a_PlayerUUID, const cPlayerListCallback & a_Callback);  // >> EXPORTED IN MANUALBINDINGS <<
+	bool DoWithPlayerByUUID(const cUUID & a_PlayerUUID, cPlayerListCallback & a_Callback);  // >> EXPORTED IN MANUALBINDINGS <<
 
 	/** Finds the player using it's complete username and calls the callback */
-	bool DoWithPlayer(const AString & a_PlayerName, const cPlayerListCallback & a_Callback);
+	bool DoWithPlayer(const AString & a_PlayerName, cPlayerListCallback & a_Callback);
 
 	/** Send playerlist of all worlds to player */
 	void SendPlayerLists(cPlayer * a_DestPlayer);
diff --git a/src/Scoreboard.cpp b/src/Scoreboard.cpp
index 5faf88f39..4dde5b2dd 100644
--- a/src/Scoreboard.cpp
+++ b/src/Scoreboard.cpp
@@ -1,4 +1,4 @@
-
+
 // Scoreboard.cpp
 
 // Implementation of a scoreboard that keeps track of specified objectives
@@ -487,7 +487,7 @@ cObjective * cScoreboard::GetObjectiveIn(eDisplaySlot a_Slot)
 
 
 
-bool cScoreboard::ForEachObjectiveWith(cObjective::eType a_Type, const cObjectiveCallback & a_Callback)
+bool cScoreboard::ForEachObjectiveWith(cObjective::eType a_Type, cObjectiveCallback & a_Callback)
 {
 	cCSLock Lock(m_CSObjectives);
 
@@ -496,7 +496,7 @@ bool cScoreboard::ForEachObjectiveWith(cObjective::eType a_Type, const cObjectiv
 		if (it->second.GetType() == a_Type)
 		{
 			// Call callback
-			if (a_Callback(it->second))
+			if (a_Callback.Item(&it->second))
 			{
 				return false;
 			}
@@ -509,14 +509,14 @@ bool cScoreboard::ForEachObjectiveWith(cObjective::eType a_Type, const cObjectiv
 
 
 
-bool cScoreboard::ForEachObjective(const cObjectiveCallback & a_Callback)
+bool cScoreboard::ForEachObjective(cObjectiveCallback & a_Callback)
 {
 	cCSLock Lock(m_CSObjectives);
 
 	for (cObjectiveMap::iterator it = m_Objectives.begin(); it != m_Objectives.end(); ++it)
 	{
 		// Call callback
-		if (a_Callback(it->second))
+		if (a_Callback.Item(&it->second))
 		{
 			return false;
 		}
@@ -528,14 +528,14 @@ bool cScoreboard::ForEachObjective(const cObjectiveCallback & a_Callback)
 
 
 
-bool cScoreboard::ForEachTeam(const cTeamCallback & a_Callback)
+bool cScoreboard::ForEachTeam(cTeamCallback & a_Callback)
 {
 	cCSLock Lock(m_CSTeams);
 
 	for (cTeamMap::iterator it = m_Teams.begin(); it != m_Teams.end(); ++it)
 	{
 		// Call callback
-		if (a_Callback(it->second))
+		if (a_Callback.Item(&it->second))
 		{
 			return false;
 		}
diff --git a/src/Scoreboard.h b/src/Scoreboard.h
index 047a0cf7b..597c502c7 100644
--- a/src/Scoreboard.h
+++ b/src/Scoreboard.h
@@ -1,4 +1,4 @@
-
+
 // Scoreboard.h
 
 // Implementation of a scoreboard that keeps track of specified objectives
@@ -11,15 +11,14 @@
 
 
 
-#include <functional>
 
 
 class cObjective;
 class cTeam;
 class cWorld;
 
-using cObjectiveCallback = std::function<bool(cObjective &)>;
-using cTeamCallback      = std::function<bool(cTeam &)>;
+typedef cItemCallback<cObjective> cObjectiveCallback;
+typedef cItemCallback<cTeam>      cTeamCallback;
 
 
 
@@ -267,15 +266,15 @@ public:
 
 	/** Execute callback for each objective with the specified type
 	Returns true if all objectives processed, false if the callback aborted by returning true. */
-	bool ForEachObjectiveWith(cObjective::eType a_Type, const cObjectiveCallback & a_Callback);
+	bool ForEachObjectiveWith(cObjective::eType a_Type, cObjectiveCallback & a_Callback);
 
 	/** Execute callback for each objective.
 	Returns true if all objectives have been processed, false if the callback aborted by returning true. */
-	bool ForEachObjective(const cObjectiveCallback & a_Callback);  // Exported in ManualBindings.cpp
+	bool ForEachObjective(cObjectiveCallback & a_Callback);  // Exported in ManualBindings.cpp
 
 	/** Execute callback for each team.
 	Returns true if all teams have been processed, false if the callback aborted by returning true. */
-	bool ForEachTeam(const cTeamCallback & a_Callback);  // Exported in ManualBindings.cpp
+	bool ForEachTeam(cTeamCallback & a_Callback);  // Exported in ManualBindings.cpp
 
 	void SetDisplay(cObjective * a_Objective, eDisplaySlot a_Slot);
 
diff --git a/src/Server.cpp b/src/Server.cpp
index 89dccb1f1..6ddb14ae5 100644
--- a/src/Server.cpp
+++ b/src/Server.cpp
@@ -498,20 +498,26 @@ void cServer::ExecuteConsoleCommand(const AString & a_Cmd, cCommandOutputCallbac
 	}
 	if (split[0] == "destroyentities")
 	{
-		cRoot::Get()->ForEachWorld([](cWorld & a_World)
+		class WorldCallback : public cWorldListCallback
+		{
+			virtual bool Item(cWorld * a_World) override
 			{
-				a_World.ForEachEntity([](cEntity & a_Entity)
+				class EntityCallback : public cEntityCallback
+				{
+					virtual bool Item(cEntity * a_Entity) override
 					{
-						if (!a_Entity.IsPlayer())
+						if (!a_Entity->IsPlayer())
 						{
-							a_Entity.Destroy();
+							a_Entity->Destroy();
 						}
 						return false;
 					}
-				);
+				} EC;
+				a_World->ForEachEntity(EC);
 				return false;
 			}
-		);
+		} WC;
+		cRoot::Get()->ForEachWorld(WC);
 		a_Output.Out("Destroyed all entities");
 		a_Output.Finished();
 		return;
diff --git a/src/Simulator/IncrementalRedstoneSimulator/CommandBlockHandler.h b/src/Simulator/IncrementalRedstoneSimulator/CommandBlockHandler.h
index de0f23620..91fbe05ff 100644
--- a/src/Simulator/IncrementalRedstoneSimulator/CommandBlockHandler.h
+++ b/src/Simulator/IncrementalRedstoneSimulator/CommandBlockHandler.h
@@ -44,12 +44,17 @@ public:
 			return {};
 		}
 
-		a_World.DoWithCommandBlockAt(a_Position.x, a_Position.y, a_Position.z, [](cCommandBlockEntity & a_CommandBlock)
+		class cSetPowerToCommandBlock : public cCommandBlockCallback
+		{
+		public:
+			virtual bool Item(cCommandBlockEntity * a_CommandBlock) override
 			{
-				a_CommandBlock.Activate();
+				a_CommandBlock->Activate();
 				return false;
 			}
-		);
+		} CmdBlockSP;
+
+		a_World.DoWithCommandBlockAt(a_Position.x, a_Position.y, a_Position.z, CmdBlockSP);
 		return {};
 	}
 
diff --git a/src/Simulator/IncrementalRedstoneSimulator/DropSpenserHandler.h b/src/Simulator/IncrementalRedstoneSimulator/DropSpenserHandler.h
index 4974324a0..62b37eb1d 100644
--- a/src/Simulator/IncrementalRedstoneSimulator/DropSpenserHandler.h
+++ b/src/Simulator/IncrementalRedstoneSimulator/DropSpenserHandler.h
@@ -56,12 +56,18 @@ public:
 		bool WasPoweredPreviously = IsActivated(a_Meta);
 		if (IsPoweredNow && !WasPoweredPreviously)
 		{
-			a_World.DoWithDropSpenserAt(a_Position.x, a_Position.y, a_Position.z, [](cDropSpenserEntity & a_DropSpenser)
+			class cSetPowerToDropSpenser :
+				public cDropSpenserCallback
+			{
+			public:
+				virtual bool Item(cDropSpenserEntity * a_DropSpenser) override
 				{
-					a_DropSpenser.Activate();
+					a_DropSpenser->Activate();
 					return false;
 				}
-			);
+			} DrSpSP;
+
+			a_World.DoWithDropSpenserAt(a_Position.x, a_Position.y, a_Position.z, DrSpSP);
 		}
 
 		// Update the internal dropspenser state if necessary
diff --git a/src/Simulator/IncrementalRedstoneSimulator/NoteBlockHandler.h b/src/Simulator/IncrementalRedstoneSimulator/NoteBlockHandler.h
index ba6c695d6..add608654 100644
--- a/src/Simulator/IncrementalRedstoneSimulator/NoteBlockHandler.h
+++ b/src/Simulator/IncrementalRedstoneSimulator/NoteBlockHandler.h
@@ -45,12 +45,17 @@ public:
 			return {};
 		}
 
-		a_World.DoWithNoteBlockAt(a_Position.x, a_Position.y, a_Position.z, [](cNoteEntity & a_NoteBlock)
+		class cSetPowerToNoteBlock : public cNoteBlockCallback
+		{
+		public:
+			virtual bool Item(cNoteEntity * a_NoteBlock) override
 			{
-				a_NoteBlock.MakeSound();
+				a_NoteBlock->MakeSound();
 				return false;
 			}
-		);
+		} NoteBlockSP;
+
+		a_World.DoWithNoteBlockAt(a_Position.x, a_Position.y, a_Position.z, NoteBlockSP);
 
 		return {};
 	}
diff --git a/src/Simulator/IncrementalRedstoneSimulator/PressurePlateHandler.h b/src/Simulator/IncrementalRedstoneSimulator/PressurePlateHandler.h
index 93759408d..14d7baf85 100644
--- a/src/Simulator/IncrementalRedstoneSimulator/PressurePlateHandler.h
+++ b/src/Simulator/IncrementalRedstoneSimulator/PressurePlateHandler.h
@@ -27,37 +27,49 @@ public:
 	{
 		UNUSED(a_Meta);
 
-		unsigned int NumberOfEntities;
-		bool FoundPlayer;
-		a_World.ForEachEntityInBox(cBoundingBox(Vector3d(0.5, 0, 0.5) + a_Position, 0.5, 0.5), [&](cEntity & a_Entity)
+		class cPressurePlateCallback :
+			public cEntityCallback
+		{
+		public:
+			cPressurePlateCallback(void) :
+				m_NumberOfEntities(0),
+				m_FoundPlayer(false)
 			{
-				if (a_Entity.IsPlayer())
+			}
+
+			virtual bool Item(cEntity * a_Entity) override
+			{
+				if (a_Entity->IsPlayer())
 				{
-					FoundPlayer = true;
+					m_FoundPlayer = true;
 				}
 
-				NumberOfEntities++;
+				m_NumberOfEntities++;
 				return false;
 			}
-		);
+
+			unsigned int m_NumberOfEntities;
+			bool m_FoundPlayer;
+		} PressurePlateCallback;
+		a_World.ForEachEntityInBox(cBoundingBox(Vector3d(0.5, 0, 0.5) + a_Position, 0.5, 0.5), PressurePlateCallback);
 
 		switch (a_BlockType)
 		{
 			case E_BLOCK_STONE_PRESSURE_PLATE:
 			{
-				return (FoundPlayer ? 15 : 0);
+				return (PressurePlateCallback.m_FoundPlayer ? 15 : 0);
 			}
 			case E_BLOCK_WOODEN_PRESSURE_PLATE:
 			{
-				return (NumberOfEntities != 0 ? 15 : 0);
+				return (PressurePlateCallback.m_NumberOfEntities != 0 ? 15 : 0);
 			}
 			case E_BLOCK_HEAVY_WEIGHTED_PRESSURE_PLATE:
 			{
-				return std::min(static_cast<unsigned char>(CeilC(NumberOfEntities / 10.f)), static_cast<unsigned char>(15));
+				return std::min(static_cast<unsigned char>(CeilC(PressurePlateCallback.m_NumberOfEntities / 10.f)), static_cast<unsigned char>(15));
 			}
 			case E_BLOCK_LIGHT_WEIGHTED_PRESSURE_PLATE:
 			{
-				return std::min(static_cast<unsigned char>(NumberOfEntities), static_cast<unsigned char>(15));
+				return std::min(static_cast<unsigned char>(PressurePlateCallback.m_NumberOfEntities), static_cast<unsigned char>(15));
 			}
 			default:
 			{
diff --git a/src/Simulator/IncrementalRedstoneSimulator/RedstoneComparatorHandler.h b/src/Simulator/IncrementalRedstoneSimulator/RedstoneComparatorHandler.h
index 6e3d080aa..55efee6b5 100644
--- a/src/Simulator/IncrementalRedstoneSimulator/RedstoneComparatorHandler.h
+++ b/src/Simulator/IncrementalRedstoneSimulator/RedstoneComparatorHandler.h
@@ -44,12 +44,17 @@ public:
 		UNUSED(a_Position);
 		UNUSED(a_BlockType);
 
-		UInt8 SignalStrength = 0;
-		auto RearCoordinate = cBlockComparatorHandler::GetRearCoordinate(a_Position, a_Meta & 0x3);
-		a_World.DoWithBlockEntityAt(RearCoordinate.x, RearCoordinate.y, RearCoordinate.z, [&](cBlockEntity & a_BlockEntity)
+		class cContainerCallback : public cBlockEntityCallback
+		{
+		public:
+			cContainerCallback() : m_SignalStrength(0)
+			{
+			}
+
+			virtual bool Item(cBlockEntity * a_BlockEntity) override
 			{
 				// Skip BlockEntities that don't have slots
-				auto BlockEntityWithItems = dynamic_cast<cBlockEntityWithItems *>(&a_BlockEntity);
+				auto BlockEntityWithItems = dynamic_cast<cBlockEntityWithItems *>(a_BlockEntity);
 				if (BlockEntityWithItems == nullptr)
 				{
 					return false;
@@ -63,18 +68,23 @@ public:
 					Fullness += static_cast<float>(Contents.GetSlot(Slot).m_ItemCount) / Contents.GetSlot(Slot).GetMaxStackSize();
 				}
 
-				SignalStrength = (Fullness < 0.001 /* container empty? */) ? 0 : static_cast<UInt8>(1 + (Fullness / Contents.GetNumSlots()) * 14);
+				m_SignalStrength = (Fullness < 0.001 /* container empty? */) ? 0 : static_cast<unsigned char>(1 + (Fullness / Contents.GetNumSlots()) * 14);
 				return false;
 			}
-		);
-		auto RearPower = SignalStrength;
+
+			unsigned char m_SignalStrength;
+		} CCB;
+
+		auto RearCoordinate = cBlockComparatorHandler::GetRearCoordinate(a_Position, a_Meta & 0x3);
+		a_World.DoWithBlockEntityAt(RearCoordinate.x, RearCoordinate.y, RearCoordinate.z, CCB);
+		auto RearPower = CCB.m_SignalStrength;
 		auto RearType = a_World.GetBlock(RearCoordinate);
 
 		auto PotentialSourceHandler = cIncrementalRedstoneSimulator::GetComponentHandler(RearType);
 		if (PotentialSourceHandler != nullptr)
 		{
 			NIBBLETYPE RearMeta = a_World.GetBlockMeta(RearCoordinate);
-			RearPower = std::max(SignalStrength, PotentialSourceHandler->GetPowerDeliveredToPosition(a_World, RearCoordinate, RearType, RearMeta, a_Position, a_BlockType));
+			RearPower = std::max(CCB.m_SignalStrength, PotentialSourceHandler->GetPowerDeliveredToPosition(a_World, RearCoordinate, RearType, RearMeta, a_Position, a_BlockType));
 		}
 
 		return RearPower;
diff --git a/src/Simulator/IncrementalRedstoneSimulator/TrappedChestHandler.h b/src/Simulator/IncrementalRedstoneSimulator/TrappedChestHandler.h
index d280f73e3..8b7b82d49 100644
--- a/src/Simulator/IncrementalRedstoneSimulator/TrappedChestHandler.h
+++ b/src/Simulator/IncrementalRedstoneSimulator/TrappedChestHandler.h
@@ -1,4 +1,4 @@
-
+
 #pragma once
 
 #include "RedstoneHandler.h"
@@ -28,15 +28,38 @@ public:
 		UNUSED(a_BlockType);
 		UNUSED(a_Meta);
 
-		int NumberOfPlayers = 0;
-		VERIFY(!a_World.DoWithChestAt(a_Position.x, a_Position.y, a_Position.z, [&](cChestEntity & a_Chest)
+		class cGetTrappedChestPlayers :
+			public cItemCallback<cChestEntity>
+		{
+		public:
+			cGetTrappedChestPlayers(void) :
+				m_NumberOfPlayers(0)
+			{
+			}
+
+			virtual ~cGetTrappedChestPlayers() override
+			{
+			}
+
+			virtual bool Item(cChestEntity * a_Chest) override
 			{
-				ASSERT(a_Chest.GetBlockType() == E_BLOCK_TRAPPED_CHEST);
-				NumberOfPlayers = a_Chest.GetNumberOfPlayers();
+				ASSERT(a_Chest->GetBlockType() == E_BLOCK_TRAPPED_CHEST);
+				m_NumberOfPlayers = a_Chest->GetNumberOfPlayers();
 				return true;
 			}
-		));
-		return static_cast<unsigned char>(std::min(NumberOfPlayers, 15));
+
+			unsigned char GetPowerLevel(void) const
+			{
+				return static_cast<unsigned char>(std::min(m_NumberOfPlayers, 15));
+			}
+
+		private:
+			int m_NumberOfPlayers;
+
+		} GTCP;
+
+		VERIFY(!a_World.DoWithChestAt(a_Position.x, a_Position.y, a_Position.z, GTCP));
+		return GTCP.GetPowerLevel();
 	}
 
 	virtual cVector3iArray Update(cWorld & a_World, const Vector3i & a_Position, BLOCKTYPE a_BlockType, NIBBLETYPE a_Meta, PoweringData a_PoweringData) const override
diff --git a/src/Simulator/IncrementalRedstoneSimulator/TripwireHookHandler.h b/src/Simulator/IncrementalRedstoneSimulator/TripwireHookHandler.h
index 2fb85f58c..85c05430c 100644
--- a/src/Simulator/IncrementalRedstoneSimulator/TripwireHookHandler.h
+++ b/src/Simulator/IncrementalRedstoneSimulator/TripwireHookHandler.h
@@ -39,7 +39,26 @@ public:
 
 			if (Type == E_BLOCK_TRIPWIRE)
 			{
-				if (!a_World.ForEachEntityInBox(cBoundingBox(Vector3d(0.5, 0, 0.5) + Position, 0.5, 0.5), [](cEntity &) { return true; }))
+				class cTripwireCallback :
+					public cEntityCallback
+				{
+				public:
+					cTripwireCallback(void) :
+						m_NumberOfEntities(0),
+						m_FoundPlayer(false)
+					{
+					}
+
+					virtual bool Item(cEntity * a_Entity) override
+					{
+						return true;
+					}
+
+					unsigned int m_NumberOfEntities;
+					bool m_FoundPlayer;
+				} TripwireCallback;
+
+				if (!a_World.ForEachEntityInBox(cBoundingBox(Vector3d(0.5, 0, 0.5) + Position, 0.5, 0.5), TripwireCallback))
 				{
 					FoundActivated = true;
 				}
diff --git a/src/UI/Window.cpp b/src/UI/Window.cpp
index 9fbc4d988..8bbc4f482 100644
--- a/src/UI/Window.cpp
+++ b/src/UI/Window.cpp
@@ -1,4 +1,4 @@
-#include "Globals.h"  // NOTE: MSVC stupidness requires this to be the same across all modules
+#include "Globals.h"  // NOTE: MSVC stupidness requires this to be the same across all modules
 
 #include "Window.h"
 #include "WindowOwner.h"
@@ -362,12 +362,12 @@ void cWindow::OwnerDestroyed()
 
 
 
-bool cWindow::ForEachPlayer(const cPlayerListCallback & a_Callback)
+bool cWindow::ForEachPlayer(cItemCallback<cPlayer> & a_Callback)
 {
 	cCSLock Lock(m_CS);
-	for (auto & Player : m_OpenedBy)
+	for (cPlayerList::iterator itr = m_OpenedBy.begin(), end = m_OpenedBy.end(); itr != end; ++itr)
 	{
-		if (a_Callback(*Player))
+		if (a_Callback.Item(*itr))
 		{
 			return false;
 		}
@@ -379,12 +379,12 @@ bool cWindow::ForEachPlayer(const cPlayerListCallback & a_Callback)
 
 
 
-bool cWindow::ForEachClient(cClientHandleCallback & a_Callback)
+bool cWindow::ForEachClient(cItemCallback<cClientHandle> & a_Callback)
 {
 	cCSLock Lock(m_CS);
-	for (auto & Player : m_OpenedBy)
+	for (cPlayerList::iterator itr = m_OpenedBy.begin(), end = m_OpenedBy.end(); itr != end; ++itr)
 	{
-		if (a_Callback(*Player->GetClientHandle()))
+		if (a_Callback.Item((*itr)->GetClientHandle()))
 		{
 			return false;
 		}
diff --git a/src/UI/Window.h b/src/UI/Window.h
index f2023c731..d7a29dc47 100644
--- a/src/UI/Window.h
+++ b/src/UI/Window.h
@@ -1,4 +1,4 @@
-
+
 // Window.h
 
 // Interfaces to the cWindow class representing a UI window for a specific block
@@ -9,7 +9,6 @@
 
 #pragma once
 
-#include <functional>
 #include "../ItemGrid.h"
 
 
@@ -32,8 +31,7 @@ class cWorld;
 
 typedef std::list<cPlayer *> cPlayerList;
 typedef std::vector<cSlotArea *> cSlotAreas;
-using cPlayerListCallback   = std::function<bool(cPlayer       &)>;
-using cClientHandleCallback = std::function<bool(cClientHandle &)>;
+
 
 
 
@@ -153,10 +151,10 @@ public:
 	void OwnerDestroyed(void);
 
 	/** Calls the callback safely for each player that has this window open; returns true if all players have been enumerated */
-	bool ForEachPlayer(const cPlayerListCallback & a_Callback);
+	bool ForEachPlayer(cItemCallback<cPlayer> & a_Callback);
 
 	/** Calls the callback safely for each client that has this window open; returns true if all clients have been enumerated */
-	bool ForEachClient(cClientHandleCallback & a_Callback);
+	bool ForEachClient(cItemCallback<cClientHandle> & a_Callback);
 
 	/** Called on shift-clicking to distribute the stack into other areas; Modifies a_ItemStack as it is distributed!
 	if a_ShouldApply is true, the changes are written into the slots;
diff --git a/src/WebAdmin.cpp b/src/WebAdmin.cpp
index 335b6b94e..eefe57b73 100644
--- a/src/WebAdmin.cpp
+++ b/src/WebAdmin.cpp
@@ -22,6 +22,30 @@ static const char DEFAULT_WEBADMIN_PORTS[] = "8080";
 
 
 ////////////////////////////////////////////////////////////////////////////////
+// cPlayerAccum:
+
+/** Helper class - appends all player names together in an HTML list */
+class cPlayerAccum :
+	public cPlayerListCallback
+{
+	virtual bool Item(cPlayer * a_Player) override
+	{
+		m_Contents.append("<li>");
+		m_Contents.append(a_Player->GetName());
+		m_Contents.append("</li>");
+		return false;
+	}
+
+public:
+
+	AString m_Contents;
+} ;
+
+
+
+
+
+////////////////////////////////////////////////////////////////////////////////
 // cWebadminRequestData
 
 /** The form parser callbacks for requests in the "/webadmin" and "/~webadmin" paths */
diff --git a/src/World.cpp b/src/World.cpp
index 9baf9500a..acec3049e 100644
--- a/src/World.cpp
+++ b/src/World.cpp
@@ -1,4 +1,4 @@
-
+
 #include "Globals.h"  // NOTE: MSVC stupidness requires this to be the same across all modules
 
 #include "World.h"
@@ -1117,52 +1117,59 @@ void cWorld::TickMobs(std::chrono::milliseconds a_Dt)
 			{
 				m_ChunkMap->SpawnMobs(Spawner);
 				// do the spawn
-				for (auto & Mob : Spawner.getSpawned())
+				for (cMobSpawner::tSpawnedContainer::const_iterator itr2 = Spawner.getSpawned().begin(); itr2 != Spawner.getSpawned().end(); ++itr2)
 				{
-					SpawnMobFinalize(std::move(Mob));
+					SpawnMobFinalize(std::move(const_cast<std::unique_ptr<cMonster> &>(*itr2)));
 				}
 			}
 		}  // for i - AllFamilies[]
 	}  // if (Spawning enabled)
 
-	ForEachEntity([=](cEntity & a_Entity)
+	class cCallback : public cEntityCallback
+	{
+		virtual bool Item(cEntity * a_Entity) override
 		{
-			if (!a_Entity.IsMob())
+			if (!a_Entity->IsMob())
 			{
 				return false;
 			}
-			if (!a_Entity.IsTicking())
+			if (!a_Entity->IsTicking())
 			{
 				return false;
 			}
 
-			auto & Monster = static_cast<cMonster &>(a_Entity);
-			ASSERT(Monster.GetParentChunk() != nullptr);  // A ticking entity must have a valid parent chunk
+			auto Monster = static_cast<cMonster *>(a_Entity);
+			ASSERT(Monster->GetParentChunk() != nullptr);  // A ticking entity must have a valid parent chunk
 
 			// Tick close mobs
-			if (Monster.GetParentChunk()->HasAnyClients())
+			if (Monster->GetParentChunk()->HasAnyClients())
 			{
-				Monster.Tick(a_Dt, *(a_Entity.GetParentChunk()));
+				Monster->Tick(m_Dt, *(a_Entity->GetParentChunk()));
 			}
 			// Destroy far hostile mobs except if last target was a player
-			else if ((Monster.GetMobFamily() == cMonster::eFamily::mfHostile) && !Monster.WasLastTargetAPlayer())
+			else if ((Monster->GetMobFamily() == cMonster::eFamily::mfHostile) && !Monster->WasLastTargetAPlayer())
 			{
-				if (Monster.GetMobType() != eMonsterType::mtWolf)
+				if (Monster->GetMobType() != eMonsterType::mtWolf)
 				{
-					Monster.Destroy(true);
+					Monster->Destroy(true);
 				}
 				else
 				{
-					auto & Wolf = static_cast<cWolf &>(Monster);
-					if (Wolf.IsAngry())
+					auto Wolf = static_cast<cWolf *>(Monster);
+					if (Wolf->IsAngry())
 					{
-						Monster.Destroy(true);
+						Monster->Destroy(true);
 					}
 				}
 			}
 			return false;
 		}
-	);
+	public:
+		std::chrono::milliseconds m_Dt;
+	} Callback;
+
+	Callback.m_Dt = a_Dt;
+	ForEachEntity(Callback);
 }
 
 
@@ -1314,7 +1321,7 @@ void cWorld::WakeUpSimulatorsInArea(const cCuboid & a_Area)
 
 
 
-bool cWorld::ForEachBlockEntityInChunk(int a_ChunkX, int a_ChunkZ, const cBlockEntityCallback & a_Callback)
+bool cWorld::ForEachBlockEntityInChunk(int a_ChunkX, int a_ChunkZ, cBlockEntityCallback & a_Callback)
 {
 	return m_ChunkMap->ForEachBlockEntityInChunk(a_ChunkX, a_ChunkZ, a_Callback);
 }
@@ -1323,7 +1330,7 @@ bool cWorld::ForEachBlockEntityInChunk(int a_ChunkX, int a_ChunkZ, const cBlockE
 
 
 
-bool cWorld::ForEachBrewingstandInChunk(int a_ChunkX, int a_ChunkZ, const cBrewingstandCallback & a_Callback)
+bool cWorld::ForEachBrewingstandInChunk(int a_ChunkX, int a_ChunkZ, cBrewingstandCallback & a_Callback)
 {
 	return m_ChunkMap->ForEachBrewingstandInChunk(a_ChunkX, a_ChunkZ, a_Callback);
 }
@@ -1332,7 +1339,7 @@ bool cWorld::ForEachBrewingstandInChunk(int a_ChunkX, int a_ChunkZ, const cBrewi
 
 
 
-bool cWorld::ForEachChestInChunk(int a_ChunkX, int a_ChunkZ, const cChestCallback & a_Callback)
+bool cWorld::ForEachChestInChunk(int a_ChunkX, int a_ChunkZ, cChestCallback & a_Callback)
 {
 	return m_ChunkMap->ForEachChestInChunk(a_ChunkX, a_ChunkZ, a_Callback);
 }
@@ -1341,7 +1348,7 @@ bool cWorld::ForEachChestInChunk(int a_ChunkX, int a_ChunkZ, const cChestCallbac
 
 
 
-bool cWorld::ForEachDispenserInChunk(int a_ChunkX, int a_ChunkZ, const cDispenserCallback & a_Callback)
+bool cWorld::ForEachDispenserInChunk(int a_ChunkX, int a_ChunkZ, cDispenserCallback & a_Callback)
 {
 	return m_ChunkMap->ForEachDispenserInChunk(a_ChunkX, a_ChunkZ, a_Callback);
 }
@@ -1350,7 +1357,7 @@ bool cWorld::ForEachDispenserInChunk(int a_ChunkX, int a_ChunkZ, const cDispense
 
 
 
-bool cWorld::ForEachDropperInChunk(int a_ChunkX, int a_ChunkZ, const cDropperCallback & a_Callback)
+bool cWorld::ForEachDropperInChunk(int a_ChunkX, int a_ChunkZ, cDropperCallback & a_Callback)
 {
 	return m_ChunkMap->ForEachDropperInChunk(a_ChunkX, a_ChunkZ, a_Callback);
 }
@@ -1359,7 +1366,7 @@ bool cWorld::ForEachDropperInChunk(int a_ChunkX, int a_ChunkZ, const cDropperCal
 
 
 
-bool cWorld::ForEachDropSpenserInChunk(int a_ChunkX, int a_ChunkZ, const cDropSpenserCallback & a_Callback)
+bool cWorld::ForEachDropSpenserInChunk(int a_ChunkX, int a_ChunkZ, cDropSpenserCallback & a_Callback)
 {
 	return m_ChunkMap->ForEachDropSpenserInChunk(a_ChunkX, a_ChunkZ, a_Callback);
 }
@@ -1368,7 +1375,7 @@ bool cWorld::ForEachDropSpenserInChunk(int a_ChunkX, int a_ChunkZ, const cDropSp
 
 
 
-bool cWorld::ForEachFurnaceInChunk(int a_ChunkX, int a_ChunkZ, const cFurnaceCallback & a_Callback)
+bool cWorld::ForEachFurnaceInChunk(int a_ChunkX, int a_ChunkZ, cFurnaceCallback & a_Callback)
 {
 	return m_ChunkMap->ForEachFurnaceInChunk(a_ChunkX, a_ChunkZ, a_Callback);
 }
@@ -1423,7 +1430,7 @@ void cWorld::DoExplosionAt(double a_ExplosionSize, double a_BlockX, double a_Blo
 
 
 
-bool cWorld::DoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBlockEntityCallback & a_Callback)
+bool cWorld::DoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBlockEntityCallback & a_Callback)
 {
 	return m_ChunkMap->DoWithBlockEntityAt(a_BlockX, a_BlockY, a_BlockZ, a_Callback);
 }
@@ -1432,7 +1439,7 @@ bool cWorld::DoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, const
 
 
 
-bool cWorld::DoWithBeaconAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBeaconCallback & a_Callback)
+bool cWorld::DoWithBeaconAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBeaconCallback & a_Callback)
 {
 	return m_ChunkMap->DoWithBeaconAt(a_BlockX, a_BlockY, a_BlockZ, a_Callback);
 }
@@ -1441,7 +1448,7 @@ bool cWorld::DoWithBeaconAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBea
 
 
 
-bool cWorld::DoWithBedAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBedCallback & a_Callback)
+bool cWorld::DoWithBedAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBedCallback & a_Callback)
 {
 	return m_ChunkMap->DoWithBedAt(a_BlockX, a_BlockY, a_BlockZ, a_Callback);
 }
@@ -1450,7 +1457,7 @@ bool cWorld::DoWithBedAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBedCal
 
 
 
-bool cWorld::DoWithBrewingstandAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBrewingstandCallback & a_Callback)
+bool cWorld::DoWithBrewingstandAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBrewingstandCallback & a_Callback)
 {
 	return m_ChunkMap->DoWithBrewingstandAt(a_BlockX, a_BlockY, a_BlockZ, a_Callback);
 }
@@ -1459,7 +1466,7 @@ bool cWorld::DoWithBrewingstandAt(int a_BlockX, int a_BlockY, int a_BlockZ, cons
 
 
 
-bool cWorld::DoWithChestAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cChestCallback & a_Callback)
+bool cWorld::DoWithChestAt(int a_BlockX, int a_BlockY, int a_BlockZ, cChestCallback & a_Callback)
 {
 	return m_ChunkMap->DoWithChestAt(a_BlockX, a_BlockY, a_BlockZ, a_Callback);
 }
@@ -1468,7 +1475,7 @@ bool cWorld::DoWithChestAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cChes
 
 
 
-bool cWorld::DoWithDispenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cDispenserCallback & a_Callback)
+bool cWorld::DoWithDispenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, cDispenserCallback & a_Callback)
 {
 	return m_ChunkMap->DoWithDispenserAt(a_BlockX, a_BlockY, a_BlockZ, a_Callback);
 }
@@ -1477,7 +1484,7 @@ bool cWorld::DoWithDispenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, const c
 
 
 
-bool cWorld::DoWithDropperAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cDropperCallback & a_Callback)
+bool cWorld::DoWithDropperAt(int a_BlockX, int a_BlockY, int a_BlockZ, cDropperCallback & a_Callback)
 {
 	return m_ChunkMap->DoWithDropperAt(a_BlockX, a_BlockY, a_BlockZ, a_Callback);
 }
@@ -1486,7 +1493,7 @@ bool cWorld::DoWithDropperAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cDr
 
 
 
-bool cWorld::DoWithDropSpenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cDropSpenserCallback & a_Callback)
+bool cWorld::DoWithDropSpenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, cDropSpenserCallback & a_Callback)
 {
 	return m_ChunkMap->DoWithDropSpenserAt(a_BlockX, a_BlockY, a_BlockZ, a_Callback);
 }
@@ -1495,7 +1502,7 @@ bool cWorld::DoWithDropSpenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, const
 
 
 
-bool cWorld::DoWithFurnaceAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cFurnaceCallback & a_Callback)
+bool cWorld::DoWithFurnaceAt(int a_BlockX, int a_BlockY, int a_BlockZ, cFurnaceCallback & a_Callback)
 {
 	return m_ChunkMap->DoWithFurnaceAt(a_BlockX, a_BlockY, a_BlockZ, a_Callback);
 }
@@ -1504,7 +1511,7 @@ bool cWorld::DoWithFurnaceAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cFu
 
 
 
-bool cWorld::DoWithNoteBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cNoteBlockCallback & a_Callback)
+bool cWorld::DoWithNoteBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, cNoteBlockCallback & a_Callback)
 {
 	return m_ChunkMap->DoWithNoteBlockAt(a_BlockX, a_BlockY, a_BlockZ, a_Callback);
 }
@@ -1513,7 +1520,7 @@ bool cWorld::DoWithNoteBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, const c
 
 
 
-bool cWorld::DoWithCommandBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cCommandBlockCallback & a_Callback)
+bool cWorld::DoWithCommandBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, cCommandBlockCallback & a_Callback)
 {
 	return m_ChunkMap->DoWithCommandBlockAt(a_BlockX, a_BlockY, a_BlockZ, a_Callback);
 }
@@ -1522,7 +1529,7 @@ bool cWorld::DoWithCommandBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, cons
 
 
 
-bool cWorld::DoWithMobHeadAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cMobHeadCallback & a_Callback)
+bool cWorld::DoWithMobHeadAt(int a_BlockX, int a_BlockY, int a_BlockZ, cMobHeadCallback & a_Callback)
 {
 	return m_ChunkMap->DoWithMobHeadAt(a_BlockX, a_BlockY, a_BlockZ, a_Callback);
 }
@@ -1531,7 +1538,7 @@ bool cWorld::DoWithMobHeadAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cMo
 
 
 
-bool cWorld::DoWithFlowerPotAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cFlowerPotCallback & a_Callback)
+bool cWorld::DoWithFlowerPotAt(int a_BlockX, int a_BlockY, int a_BlockZ, cFlowerPotCallback & a_Callback)
 {
 	return m_ChunkMap->DoWithFlowerPotAt(a_BlockX, a_BlockY, a_BlockZ, a_Callback);
 }
@@ -1549,7 +1556,7 @@ bool cWorld::GetSignLines(int a_BlockX, int a_BlockY, int a_BlockZ, AString & a_
 
 
 
-bool cWorld::DoWithChunk(int a_ChunkX, int a_ChunkZ, const cChunkCallback & a_Callback)
+bool cWorld::DoWithChunk(int a_ChunkX, int a_ChunkZ, cChunkCallback & a_Callback)
 {
 	return m_ChunkMap->DoWithChunk(a_ChunkX, a_ChunkZ, a_Callback);
 }
@@ -1558,7 +1565,31 @@ bool cWorld::DoWithChunk(int a_ChunkX, int a_ChunkZ, const cChunkCallback & a_Ca
 
 
 
-bool cWorld::DoWithChunkAt(Vector3i a_BlockPos, const cChunkCallback & a_Callback)
+bool cWorld::DoWithChunk(int a_ChunkX, int a_ChunkZ, std::function<bool(cChunk &)> a_Callback)
+{
+	struct cCallBackWrapper : cChunkCallback
+	{
+		cCallBackWrapper(std::function<bool(cChunk &)> a_InnerCallback) :
+			m_Callback(a_InnerCallback)
+		{
+		}
+
+		virtual bool Item(cChunk * a_Chunk)
+		{
+			return m_Callback(*a_Chunk);
+		}
+
+	private:
+		std::function<bool(cChunk &)> m_Callback;
+	} callback(a_Callback);
+	return m_ChunkMap->DoWithChunk(a_ChunkX, a_ChunkZ, callback);
+}
+
+
+
+
+
+bool cWorld::DoWithChunkAt(Vector3i a_BlockPos, std::function<bool(cChunk &)>  a_Callback)
 {
 	return m_ChunkMap->DoWithChunkAt(a_BlockPos, a_Callback);
 }
@@ -3132,13 +3163,18 @@ bool cWorld::IsPlayerReferencedInWorldOrChunk(cPlayer & a_Player)
 
 
 
-bool cWorld::ForEachPlayer(const cPlayerListCallback & a_Callback)
+bool cWorld::ForEachPlayer(cPlayerListCallback & a_Callback)
 {
 	// Calls the callback for each player in the list
 	cCSLock Lock(m_CSPlayers);
-	for (auto & Player : m_Players)
+	for (cPlayerList::iterator itr = m_Players.begin(), itr2 = itr; itr != m_Players.end(); itr = itr2)
 	{
-		if (Player->IsTicking() && a_Callback(*Player))
+		++itr2;
+		if (!(*itr)->IsTicking())
+		{
+			continue;
+		}
+		if (a_Callback.Item(*itr))
 		{
 			return false;
 		}
@@ -3150,15 +3186,19 @@ bool cWorld::ForEachPlayer(const cPlayerListCallback & a_Callback)
 
 
 
-bool cWorld::DoWithPlayer(const AString & a_PlayerName, const cPlayerListCallback & a_Callback)
+bool cWorld::DoWithPlayer(const AString & a_PlayerName, cPlayerListCallback & a_Callback)
 {
 	// Calls the callback for the specified player in the list
 	cCSLock Lock(m_CSPlayers);
-	for (auto & Player : m_Players)
+	for (cPlayerList::iterator itr = m_Players.begin(); itr != m_Players.end(); ++itr)
 	{
-		if (Player->IsTicking() && (NoCaseCompare(Player->GetName(), a_PlayerName) == 0))
+		if (!(*itr)->IsTicking())
+		{
+			continue;
+		}
+		if (NoCaseCompare((*itr)->GetName(), a_PlayerName) == 0)
 		{
-			a_Callback(*Player);
+			a_Callback.Item(*itr);
 			return true;
 		}
 	}  // for itr - m_Players[]
@@ -3169,7 +3209,7 @@ bool cWorld::DoWithPlayer(const AString & a_PlayerName, const cPlayerListCallbac
 
 
 
-bool cWorld::FindAndDoWithPlayer(const AString & a_PlayerNameHint, const cPlayerListCallback & a_Callback)
+bool cWorld::FindAndDoWithPlayer(const AString & a_PlayerNameHint, cPlayerListCallback & a_Callback)
 {
 	cPlayer * BestMatch = nullptr;
 	size_t BestRating = 0;
@@ -3196,7 +3236,7 @@ bool cWorld::FindAndDoWithPlayer(const AString & a_PlayerNameHint, const cPlayer
 
 	if (BestMatch != nullptr)
 	{
-		return a_Callback(*BestMatch);
+		return a_Callback.Item (BestMatch);
 	}
 	return false;
 }
@@ -3205,14 +3245,27 @@ bool cWorld::FindAndDoWithPlayer(const AString & a_PlayerNameHint, const cPlayer
 
 
 
-bool cWorld::DoWithPlayerByUUID(const cUUID & a_PlayerUUID, const cPlayerListCallback & a_Callback)
+bool cWorld::DoWithPlayerByUUID(const cUUID & a_PlayerUUID, cPlayerListCallback & a_Callback)
+{
+	return DoWithPlayerByUUID(a_PlayerUUID, std::bind(&cPlayerListCallback::Item, &a_Callback, std::placeholders::_1));
+}
+
+
+
+
+
+bool cWorld::DoWithPlayerByUUID(const cUUID & a_PlayerUUID, cLambdaPlayerCallback a_Callback)
 {
 	cCSLock Lock(m_CSPlayers);
-	for (auto & Player : m_Players)
+	for (cPlayerList::iterator itr = m_Players.begin(); itr != m_Players.end(); ++itr)
 	{
-		if (Player->IsTicking() && (Player->GetUUID() == a_PlayerUUID))
+		if (!(*itr)->IsTicking())
 		{
-			return a_Callback(*Player);
+			continue;
+		}
+		if ((*itr)->GetUUID() == a_PlayerUUID)
+		{
+			return a_Callback(*itr);
 		}
 	}
 	return false;
@@ -3280,7 +3333,7 @@ void cWorld::SendPlayerList(cPlayer * a_DestPlayer)
 
 
 
-bool cWorld::ForEachEntity(const cEntityCallback & a_Callback)
+bool cWorld::ForEachEntity(cEntityCallback & a_Callback)
 {
 	return m_ChunkMap->ForEachEntity(a_Callback);
 }
@@ -3289,7 +3342,7 @@ bool cWorld::ForEachEntity(const cEntityCallback & a_Callback)
 
 
 
-bool cWorld::ForEachEntityInChunk(int a_ChunkX, int a_ChunkZ, const cEntityCallback & a_Callback)
+bool cWorld::ForEachEntityInChunk(int a_ChunkX, int a_ChunkZ, cEntityCallback & a_Callback)
 {
 	return m_ChunkMap->ForEachEntityInChunk(a_ChunkX, a_ChunkZ, a_Callback);
 }
@@ -3298,7 +3351,7 @@ bool cWorld::ForEachEntityInChunk(int a_ChunkX, int a_ChunkZ, const cEntityCallb
 
 
 
-bool cWorld::ForEachEntityInBox(const cBoundingBox & a_Box, const cEntityCallback & a_Callback)
+bool cWorld::ForEachEntityInBox(const cBoundingBox & a_Box, cEntityCallback & a_Callback)
 {
 	return m_ChunkMap->ForEachEntityInBox(a_Box, a_Callback);
 }
@@ -3307,7 +3360,16 @@ bool cWorld::ForEachEntityInBox(const cBoundingBox & a_Box, const cEntityCallbac
 
 
 
-bool cWorld::DoWithEntityByID(UInt32 a_UniqueID, const cEntityCallback & a_Callback)
+bool cWorld::DoWithEntityByID(UInt32 a_UniqueID, cEntityCallback & a_Callback)
+{
+	return DoWithEntityByID(a_UniqueID, std::bind(&cEntityCallback::Item, &a_Callback, std::placeholders::_1));
+}
+
+
+
+
+
+bool cWorld::DoWithEntityByID(UInt32 a_UniqueID, cLambdaEntityCallback a_Callback)
 {
 	// First check the entities-to-add:
 	{
@@ -3316,7 +3378,7 @@ bool cWorld::DoWithEntityByID(UInt32 a_UniqueID, const cEntityCallback & a_Callb
 		{
 			if (ent->GetUniqueID() == a_UniqueID)
 			{
-				a_Callback(*ent);
+				a_Callback(ent.get());
 				return true;
 			}
 		}  // for ent - m_EntitiesToAdd[]
@@ -3448,12 +3510,20 @@ bool cWorld::SetSignLines(int a_BlockX, int a_BlockY, int a_BlockZ, const AStrin
 
 bool cWorld::SetCommandBlockCommand(int a_BlockX, int a_BlockY, int a_BlockZ, const AString & a_Command)
 {
-	return DoWithCommandBlockAt(a_BlockX, a_BlockY, a_BlockZ, [&](cCommandBlockEntity & a_CommandBlock)
+	class cUpdateCommandBlock : public cCommandBlockCallback
+	{
+		AString m_Command;
+	public:
+		cUpdateCommandBlock(const AString & a_CallbackCommand) : m_Command(a_CallbackCommand) {}
+
+		virtual bool Item(cCommandBlockEntity * a_CommandBlock) override
 		{
-			a_CommandBlock.SetCommand(a_Command);
+			a_CommandBlock->SetCommand(m_Command);
 			return false;
 		}
-	);
+	} CmdBlockCB (a_Command);
+
+	return DoWithCommandBlockAt(a_BlockX, a_BlockY, a_BlockZ, CmdBlockCB);
 }
 
 
@@ -3548,7 +3618,7 @@ bool cWorld::ForEachChunkInRect(int a_MinChunkX, int a_MaxChunkX, int a_MinChunk
 
 
 
-bool cWorld::ForEachLoadedChunk(const std::function<bool(int, int)> & a_Callback)
+bool cWorld::ForEachLoadedChunk(std::function<bool(int, int)> a_Callback)
 {
 	return m_ChunkMap->ForEachLoadedChunk(a_Callback);
 }
@@ -3579,7 +3649,7 @@ void cWorld::QueueSaveAllChunks(void)
 void cWorld::QueueTask(std::function<void(cWorld &)> a_Task)
 {
 	cCSLock Lock(m_CSTasks);
-	m_Tasks.emplace_back(0, std::move(a_Task));
+	m_Tasks.emplace_back(0, a_Task);
 }
 
 
@@ -3593,7 +3663,7 @@ void cWorld::ScheduleTask(int a_DelayTicks, std::function<void (cWorld &)> a_Tas
 	// Insert the task into the list of scheduled tasks
 	{
 		cCSLock Lock(m_CSTasks);
-		m_Tasks.emplace_back(TargetTick, std::move(a_Task));
+		m_Tasks.emplace_back(TargetTick, a_Task);
 	}
 }
 
diff --git a/src/World.h b/src/World.h
index b627c4e95..cbaf9cb95 100644
--- a/src/World.h
+++ b/src/World.h
@@ -1,4 +1,4 @@
-
+
 #pragma once
 
 #define MAX_PLAYERS 65535
@@ -58,6 +58,21 @@ typedef std::list< std::pair< std::unique_ptr<cPlayer>, cWorld * > > cAwaitingPl
 typedef std::unique_ptr<cSetChunkData> cSetChunkDataPtr;
 typedef std::vector<cSetChunkDataPtr> cSetChunkDataPtrs;
 
+typedef cItemCallback<cPlayer>             cPlayerListCallback;
+typedef cItemCallback<cEntity>             cEntityCallback;
+typedef cItemCallback<cBeaconEntity>       cBeaconCallback;
+typedef cItemCallback<cBrewingstandEntity> cBrewingstandCallback;
+typedef cItemCallback<cChestEntity>        cChestCallback;
+typedef cItemCallback<cDispenserEntity>    cDispenserCallback;
+typedef cItemCallback<cFurnaceEntity>      cFurnaceCallback;
+typedef cItemCallback<cNoteEntity>         cNoteBlockCallback;
+typedef cItemCallback<cCommandBlockEntity> cCommandBlockCallback;
+typedef cItemCallback<cMobHeadEntity>      cMobHeadCallback;
+typedef cItemCallback<cFlowerPotEntity>    cFlowerPotCallback;
+
+typedef std::function<bool (cPlayer *)>    cLambdaPlayerCallback;
+typedef std::function<bool (cEntity *)>    cLambdaEntityCallback;
+
 
 
 
@@ -260,20 +275,21 @@ public:
 #endif
 
 	/** Calls the callback for each player in the list; returns true if all players processed, false if the callback aborted by returning true */
-	virtual bool ForEachPlayer(const cPlayerListCallback & a_Callback) override;  // >> EXPORTED IN MANUALBINDINGS <<
+	virtual bool ForEachPlayer(cPlayerListCallback & a_Callback) override;  // >> EXPORTED IN MANUALBINDINGS <<
 
 	/** Calls the callback for the player of the given name; returns true if the player was found and the callback called, false if player not found.
 	Callback return value is ignored. If there are multiple players of the same name, only (random) one is processed by the callback. */
-	bool DoWithPlayer(const AString & a_PlayerName, const cPlayerListCallback & a_Callback);  // >> EXPORTED IN MANUALBINDINGS <<
+	bool DoWithPlayer(const AString & a_PlayerName, cPlayerListCallback & a_Callback);  // >> EXPORTED IN MANUALBINDINGS <<
 
 	/** Finds a player from a partial or complete player name and calls the callback - case-insensitive */
-	bool FindAndDoWithPlayer(const AString & a_PlayerNameHint, const cPlayerListCallback & a_Callback);  // >> EXPORTED IN MANUALBINDINGS <<
+	bool FindAndDoWithPlayer(const AString & a_PlayerNameHint, cPlayerListCallback & a_Callback);  // >> EXPORTED IN MANUALBINDINGS <<
 
 	// TODO: This interface is dangerous - rewrite to DoWithClosestPlayer(pos, sight, action)
 	cPlayer * FindClosestPlayer(Vector3d a_Pos, float a_SightLimit, bool a_CheckLineOfSight = true);
 
 	/** Finds the player over his uuid and calls the callback */
-	bool DoWithPlayerByUUID(const cUUID & a_PlayerUUID, const cPlayerListCallback & a_Callback);  // >> EXPORTED IN MANUALBINDINGS <<
+	bool DoWithPlayerByUUID(const cUUID & a_PlayerUUID, cPlayerListCallback & a_Callback);  // >> EXPORTED IN MANUALBINDINGS <<
+	bool DoWithPlayerByUUID(const cUUID & a_PlayerUUID, cLambdaPlayerCallback a_Callback);  // Lambda version
 
 	void SendPlayerList(cPlayer * a_DestPlayer);  // Sends playerlist to the player
 
@@ -286,19 +302,20 @@ public:
 	bool HasEntity(UInt32 a_UniqueID);
 
 	/** Calls the callback for each entity in the entire world; returns true if all entities processed, false if the callback aborted by returning true */
-	bool ForEachEntity(const cEntityCallback & a_Callback);  // Exported in ManualBindings.cpp
+	bool ForEachEntity(cEntityCallback & a_Callback);  // Exported in ManualBindings.cpp
 
 	/** Calls the callback for each entity in the specified chunk; returns true if all entities processed, false if the callback aborted by returning true */
-	bool ForEachEntityInChunk(int a_ChunkX, int a_ChunkZ, const cEntityCallback & a_Callback);  // Exported in ManualBindings.cpp
+	bool ForEachEntityInChunk(int a_ChunkX, int a_ChunkZ, cEntityCallback & a_Callback);  // Exported in ManualBindings.cpp
 
 	/** Calls the callback for each entity that has a nonempty intersection with the specified boundingbox.
 	Returns true if all entities processed, false if the callback aborted by returning true.
 	If any chunk in the box is missing, ignores the entities in that chunk silently. */
-	virtual bool ForEachEntityInBox(const cBoundingBox & a_Box, const cEntityCallback & a_Callback) override;  // Exported in ManualBindings.cpp
+	virtual bool ForEachEntityInBox(const cBoundingBox & a_Box, cEntityCallback & a_Callback) override;  // Exported in ManualBindings.cpp
 
 	/** Calls the callback if the entity with the specified ID is found, with the entity object as the callback param.
 	Returns true if entity found and callback returned false. */
-	bool DoWithEntityByID(UInt32 a_UniqueID, const cEntityCallback & a_Callback);  // Exported in ManualBindings.cpp
+	bool DoWithEntityByID(UInt32 a_UniqueID, cEntityCallback & a_Callback);  // Exported in ManualBindings.cpp
+	bool DoWithEntityByID(UInt32 a_UniqueID, cLambdaEntityCallback a_Callback);  // Lambda version
 
 	/** Compares clients of two chunks, calls the callback accordingly */
 	void CompareChunkClients(int a_ChunkX1, int a_ChunkZ1, int a_ChunkX2, int a_ChunkZ2, cClientDiffCallback & a_Callback);
@@ -362,7 +379,7 @@ public:
 	virtual bool ForEachChunkInRect(int a_MinChunkX, int a_MaxChunkX, int a_MinChunkZ, int a_MaxChunkZ, cChunkDataCallback & a_Callback) override;
 
 	/** Calls the callback for each loaded chunk. Returns true if all chunks have been processed successfully */
-	bool ForEachLoadedChunk(const std::function<bool(int, int)> & a_Callback);
+	bool ForEachLoadedChunk(std::function<bool(int, int)> a_Callback);
 
 	// tolua_begin
 
@@ -499,25 +516,25 @@ public:
 	inline cRedstoneSimulator * GetRedstoneSimulator(void) { return m_RedstoneSimulator; }
 
 	/** Calls the callback for each block entity in the specified chunk; returns true if all block entities processed, false if the callback aborted by returning true */
-	bool ForEachBlockEntityInChunk(int a_ChunkX, int a_ChunkZ, const cBlockEntityCallback & a_Callback);  // Exported in ManualBindings.cpp
+	bool ForEachBlockEntityInChunk(int a_ChunkX, int a_ChunkZ, cBlockEntityCallback & a_Callback);  // Exported in ManualBindings.cpp
 
 	/** Calls the callback for each brewingstand in the specified chunk; returns true if all brewingstands processed, false if the callback aborted by returning true */
-	bool ForEachBrewingstandInChunk(int a_ChunkX, int a_ChunkZ, const cBrewingstandCallback & a_Callback);  // Exported in ManualBindings.cpp
+	bool ForEachBrewingstandInChunk(int a_ChunkX, int a_ChunkZ, cBrewingstandCallback & a_Callback);  // Exported in ManualBindings.cpp
 
 	/** Calls the callback for each chest in the specified chunk; returns true if all chests processed, false if the callback aborted by returning true */
-	bool ForEachChestInChunk(int a_ChunkX, int a_ChunkZ, const cChestCallback & a_Callback);  // Exported in ManualBindings.cpp
+	bool ForEachChestInChunk(int a_ChunkX, int a_ChunkZ, cChestCallback & a_Callback);  // Exported in ManualBindings.cpp
 
 	/** Calls the callback for each dispenser in the specified chunk; returns true if all dispensers processed, false if the callback aborted by returning true */
-	bool ForEachDispenserInChunk(int a_ChunkX, int a_ChunkZ, const cDispenserCallback & a_Callback);
+	bool ForEachDispenserInChunk(int a_ChunkX, int a_ChunkZ, cDispenserCallback & a_Callback);
 
 	/** Calls the callback for each dropper in the specified chunk; returns true if all droppers processed, false if the callback aborted by returning true */
-	bool ForEachDropperInChunk(int a_ChunkX, int a_ChunkZ, const cDropperCallback & a_Callback);
+	bool ForEachDropperInChunk(int a_ChunkX, int a_ChunkZ, cDropperCallback & a_Callback);
 
 	/** Calls the callback for each dropspenser in the specified chunk; returns true if all dropspensers processed, false if the callback aborted by returning true */
-	bool ForEachDropSpenserInChunk(int a_ChunkX, int a_ChunkZ, const cDropSpenserCallback & a_Callback);
+	bool ForEachDropSpenserInChunk(int a_ChunkX, int a_ChunkZ, cDropSpenserCallback & a_Callback);
 
 	/** Calls the callback for each furnace in the specified chunk; returns true if all furnaces processed, false if the callback aborted by returning true */
-	bool ForEachFurnaceInChunk(int a_ChunkX, int a_ChunkZ, const cFurnaceCallback & a_Callback);  // Exported in ManualBindings.cpp
+	bool ForEachFurnaceInChunk(int a_ChunkX, int a_ChunkZ, cFurnaceCallback & a_Callback);  // Exported in ManualBindings.cpp
 
 	/** Does an explosion with the specified strength at the specified coordinates.
 	Executes the HOOK_EXPLODING and HOOK_EXPLODED hooks as part of the processing.
@@ -526,43 +543,43 @@ public:
 	virtual void DoExplosionAt(double a_ExplosionSize, double a_BlockX, double a_BlockY, double a_BlockZ, bool a_CanCauseFire, eExplosionSource a_Source, void * a_SourceData) override;
 
 	/** Calls the callback for the block entity at the specified coords; returns false if there's no block entity at those coords, true if found */
-	virtual bool DoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBlockEntityCallback & a_Callback) override;  // Exported in ManualBindings.cpp
+	virtual bool DoWithBlockEntityAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBlockEntityCallback & a_Callback) override;  // Exported in ManualBindings.cpp
 
 	/** Calls the callback for the beacon at the specified coords; returns false if there's no beacon at those coords, true if found */
-	bool DoWithBeaconAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBeaconCallback & a_Callback);  // Exported in ManualBindings.cpp
+	bool DoWithBeaconAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBeaconCallback & a_Callback);  // Exported in ManualBindings.cpp
 
 	/** Calls the callback for the bed at the specified coords; returns false if there's no bed at those coords, true if found */
-	virtual bool DoWithBedAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBedCallback & a_Callback) override;  // Exported in ManualBindings.cpp
+	virtual bool DoWithBedAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBedCallback & a_Callback) override;  // Exported in ManualBindings.cpp
 
 	/** Calls the callback for the brewingstand at the specified coords; returns false if there's no brewingstand at those coords, true if found */
-	bool DoWithBrewingstandAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cBrewingstandCallback & a_Callback);  // Lua-acessible
+	bool DoWithBrewingstandAt(int a_BlockX, int a_BlockY, int a_BlockZ, cBrewingstandCallback & a_Callback);  // Lua-acessible
 
 	/** Calls the callback for the chest at the specified coords; returns false if there's no chest at those coords, true if found */
-	bool DoWithChestAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cChestCallback & a_Callback);  // Exported in ManualBindings.cpp
+	bool DoWithChestAt(int a_BlockX, int a_BlockY, int a_BlockZ, cChestCallback & a_Callback);  // Exported in ManualBindings.cpp
 
 	/** Calls the callback for the dispenser at the specified coords; returns false if there's no dispenser at those coords or callback returns true, returns true if found */
-	bool DoWithDispenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cDispenserCallback & a_Callback);  // Exported in ManualBindings.cpp
+	bool DoWithDispenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, cDispenserCallback & a_Callback);  // Exported in ManualBindings.cpp
 
 	/** Calls the callback for the dropper at the specified coords; returns false if there's no dropper at those coords or callback returns true, returns true if found */
-	bool DoWithDropperAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cDropperCallback & a_Callback);  // Exported in ManualBindings.cpp
+	bool DoWithDropperAt(int a_BlockX, int a_BlockY, int a_BlockZ, cDropperCallback & a_Callback);  // Exported in ManualBindings.cpp
 
 	/** Calls the callback for the dropspenser at the specified coords; returns false if there's no dropspenser at those coords or callback returns true, returns true if found */
-	bool DoWithDropSpenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cDropSpenserCallback & a_Callback);  // Exported in ManualBindings.cpp
+	bool DoWithDropSpenserAt(int a_BlockX, int a_BlockY, int a_BlockZ, cDropSpenserCallback & a_Callback);  // Exported in ManualBindings.cpp
 
 	/** Calls the callback for the furnace at the specified coords; returns false if there's no furnace at those coords or callback returns true, returns true if found */
-	bool DoWithFurnaceAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cFurnaceCallback & a_Callback);  // Exported in ManualBindings.cpp
+	bool DoWithFurnaceAt(int a_BlockX, int a_BlockY, int a_BlockZ, cFurnaceCallback & a_Callback);  // Exported in ManualBindings.cpp
 
 	/** Calls the callback for the noteblock at the specified coords; returns false if there's no noteblock at those coords or callback returns true, returns true if found */
-	bool DoWithNoteBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cNoteBlockCallback & a_Callback);  // Exported in ManualBindings.cpp
+	bool DoWithNoteBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, cNoteBlockCallback & a_Callback);  // Exported in ManualBindings.cpp
 
 	/** Calls the callback for the command block at the specified coords; returns false if there's no command block at those coords or callback returns true, returns true if found */
-	bool DoWithCommandBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cCommandBlockCallback & a_Callback);  // Exported in ManualBindings.cpp
+	bool DoWithCommandBlockAt(int a_BlockX, int a_BlockY, int a_BlockZ, cCommandBlockCallback & a_Callback);  // Exported in ManualBindings.cpp
 
 	/** Calls the callback for the mob head block at the specified coords; returns false if there's no mob head block at those coords or callback returns true, returns true if found */
-	bool DoWithMobHeadAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cMobHeadCallback & a_Callback);  // Exported in ManualBindings.cpp
+	bool DoWithMobHeadAt(int a_BlockX, int a_BlockY, int a_BlockZ, cMobHeadCallback & a_Callback);  // Exported in ManualBindings.cpp
 
 	/** Calls the callback for the flower pot at the specified coords; returns false if there's no flower pot at those coords or callback returns true, returns true if found */
-	bool DoWithFlowerPotAt(int a_BlockX, int a_BlockY, int a_BlockZ, const cFlowerPotCallback & a_Callback);  // Exported in ManualBindings.cpp
+	bool DoWithFlowerPotAt(int a_BlockX, int a_BlockY, int a_BlockZ, cFlowerPotCallback & a_Callback);  // Exported in ManualBindings.cpp
 
 	/** Retrieves the test on the sign at the specified coords; returns false if there's no sign at those coords, true if found */
 	bool GetSignLines (int a_BlockX, int a_BlockY, int a_BlockZ, AString & a_Line1, AString & a_Line2, AString & a_Line3, AString & a_Line4);  // Exported in ManualBindings.cpp
@@ -570,13 +587,13 @@ public:
 	/** a_Player is using block entity at [x, y, z], handle that: */
 	void UseBlockEntity(cPlayer * a_Player, int a_BlockX, int a_BlockY, int a_BlockZ) {m_ChunkMap->UseBlockEntity(a_Player, a_BlockX, a_BlockY, a_BlockZ); }  // tolua_export
 
-	/** Calls the callback for the chunk specified, with ChunkMapCS locked.
-	Returns false if the chunk doesn't exist, otherwise returns the same value as the callback */
-	bool DoWithChunk(int a_ChunkX, int a_ChunkZ, const cChunkCallback & a_Callback);
+	/** Calls the callback for the chunk specified, with ChunkMapCS locked; returns false if the chunk doesn't exist, otherwise returns the same value as the callback */
+	bool DoWithChunk(int a_ChunkX, int a_ChunkZ, cChunkCallback & a_Callback);
+	bool DoWithChunk(int a_ChunkX, int a_ChunkZ, std::function<bool(cChunk &)> a_Callback);
 
 	/** Calls the callback for the chunk at the block position specified, with ChunkMapCS locked.
 	Returns false if the chunk isn't loaded, otherwise returns the same value as the callback */
-	bool DoWithChunkAt(Vector3i a_BlockPos, const cChunkCallback & a_Callback);
+	bool DoWithChunkAt(Vector3i a_BlockPos, std::function<bool(cChunk &)> a_Callback);
 
 	void GrowTreeImage(const sSetBlockVector & a_Blocks);