Hack code in Box2D to notify the destruction of native object.

sources/Box2D/Box2D.h

@@ -65,4 +65,6 @@ For discussion please visit http://box2d.org/forum
 #include <Box2D/Dynamics/Joints/b2WeldJoint.h>
 #include <Box2D/Dynamics/Joints/b2WheelJoint.h>
 
+#include <Box2D/b2ObjectDestroyNotifier.h>
+
 #endif

sources/Box2D/Dynamics/Contacts/b2Contact.cpp

@@ -33,6 +33,7 @@
 #include <Box2D/Dynamics/b2Body.h>
 #include <Box2D/Dynamics/b2Fixture.h>
 #include <Box2D/Dynamics/b2World.h>
+#include <Box2D/b2ObjectDestroyNotifier.h>
 
 b2ContactRegister b2Contact::s_registers[b2Shape::e_typeCount][b2Shape::e_typeCount];
 bool b2Contact::s_initialized = false;
@@ -119,6 +120,7 @@ void b2Contact::Destroy(b2Contact* contact, b2BlockAllocator* allocator)
 	b2Assert(0 <= typeA && typeB < b2Shape::e_typeCount);
 	b2Assert(0 <= typeA && typeB < b2Shape::e_typeCount);
 
+    b2NotifyObjectDestroyed(contact, typeid(*contact).name());
 	b2ContactDestroyFcn* destroyFcn = s_registers[typeA][typeB].destroyFcn;
 	destroyFcn(contact, allocator);
 }

sources/Box2D/Dynamics/Joints/b2Joint.cpp

@@ -31,6 +31,7 @@
 #include <Box2D/Dynamics/b2Body.h>
 #include <Box2D/Dynamics/b2World.h>
 #include <Box2D/Common/b2BlockAllocator.h>
+#include <Box2D/b2ObjectDestroyNotifier.h>
 
 #include <new>
 
@@ -127,6 +128,7 @@ b2Joint* b2Joint::Create(const b2JointDef* def, b2BlockAllocator* allocator)
 
 void b2Joint::Destroy(b2Joint* joint, b2BlockAllocator* allocator)
 {
+    b2NotifyObjectDestroyed(joint, typeid(*joint).name());
 	joint->~b2Joint();
 	switch (joint->m_type)
 	{

sources/Box2D/Dynamics/b2World.cpp

@@ -32,6 +32,7 @@
 #include <Box2D/Collision/b2TimeOfImpact.h>
 #include <Box2D/Common/b2Draw.h>
 #include <Box2D/Common/b2Timer.h>
+#include <Box2D/b2ObjectDestroyNotifier.h>
 #include <new>
 
 b2World::b2World(const b2Vec2& gravity)
@@ -205,6 +206,7 @@ void b2World::DestroyBody(b2Body* b)
 	}
 
 	--m_bodyCount;
+    b2NotifyObjectDestroyed(b, "b2Body");
 	b->~b2Body();
 	m_blockAllocator.Free(b, sizeof(b2Body));
 }

sources/Box2D/b2ObjectDestroyNotifier.cpp

@@ -0,0 +1,16 @@
+#include "b2ObjectDestroyNotifier.h"
+
+static b2ObjectDestroyNotifer __objectDestroyNotifier = NULL;
+
+void b2SetObjectDestroyNotifier(b2ObjectDestroyNotifer notifier)
+{
+    __objectDestroyNotifier = notifier;
+}
+
+void b2NotifyObjectDestroyed(void* obj, const char* typeName /* = NULL */)
+{
+    if (__objectDestroyNotifier != NULL)
+    {
+        __objectDestroyNotifier(obj, typeName);
+    }
+}

sources/Box2D/b2ObjectDestroyNotifier.h

@@ -0,0 +1,8 @@
+#pragma once
+
+#include <stdlib.h>
+
+typedef void (*b2ObjectDestroyNotifer)(void*, const char*);
+
+void b2SetObjectDestroyNotifier(b2ObjectDestroyNotifer notifier);
+void b2NotifyObjectDestroyed(void* obj, const char* typeName = NULL);