>>>>>>>>>>>>>>> main.cpp

#include "SceneGraph.h"
#include "Entity.h"

int main() {
	Entity e;
	SceneGraph* graph = new SceneGraph();

	graph->deleteE(&e);
}


>>>>>>>>>>>>>>>>> SceneGraph.h

#ifndef SCENEGRAPH_H
#define SCENEGRAPH_H

#include <string>

using namespace std;

class Entity;

class SceneGraph {
  public:
	void deleteE(Entity* e);
	void print(string s);
};
#endif


>>>>>>>>>>>> SceneGraph.cpp


#include "SceneGraph.h"
#include "Entity.h"
#include <string>
#include <iostream>



void SceneGraph::deleteE(Entity* e) {
	e->deleteE(this);
}

void SceneGraph::print(string s) {
	cout << s << "\n";
}



>>>>>> Entity.h


#ifndef ENTITY_H
#define ENTITY_H

class SceneGraph;

class Entity {
  public:
	void deleteE(SceneGraph* e);
};
#endif


>>>>>>>>>> Entity.cpp

#include "Entity.h"
#include "SceneGraph.h"


void Entity::deleteE(SceneGraph* graph) {
	graph->print("entity::delete()");
}