refactoring my code. My headers (Header Guard Issues)

Question

I had a post similar to this awhile ago based on a error I was getting. I was able to fix it but since then I been having trouble doing things because headers keep blocking other headers from using code. Honestly, these headers are confusing me and if anyone has any resources that will address these types of issues, that will be helpful.

What I essentially want to do is be able to have rModel.h be included inside RenderEngine.h. every time I add rModel.h to RenderEngine.h, rModel.h is no longer able to use RenderEngine.h. (rModel.h has a #include of RenderEngine.h as well).

So in a nutshell, RenderEngine and rModel need to use each others functionalities. On top of all this confusion, the Main.cpp needs to use RenderEngine.

stdafx.h

#include "targetver.h"

#define WIN32_LEAN_AND_MEAN             // Exclude rarely-used stuff from Windows headers
// Windows Header Files:
#include <windows.h>

// C RunTime Header Files
#include <stdlib.h>
#include <malloc.h>
#include <memory.h>
#include <tchar.h>
#include "resource.h"

main.cpp

#include "stdafx.h"
#include "RenderEngine.h"
#include "rModel.h"

// Global Variables:

RenderEngine go;

rModel *g_pModel;

...code...........

rModel.h

#ifndef _MODEL_H
#define _MODEL_H
#include "stdafx.h"
#include <vector>
#include <string>
#include "rTri.h"
#include "RenderEngine.h"

........Code

RenderEngine.h

#pragma once
#include "stdafx.h"
#include "d3d10.h"
#include "d3dx10.h"
#include "dinput.h"
#include "rModel.h"

.......Code......

Answer 1

As I wrote in my previous answer on this question, google about Forward declaration in C++. This may solve your problems, but, again, circular header dependencies indicate poor application design.

Answer 2

At least if I understand your question correctly, you have a little bit of a problem. You basically need to structure your headers so the inclusions form a directed acyclic graph (emphasis on acyclic).

What you may have to do is break your "renderengine.h" into two pieces, one of which just contains forward declarations, and the other of which contains the rest of your current contents. You'll then include that "forward declarations" header into "rmodel.h", and include "rmodel.h" into "renderengine.h".

While there are times that this is unavoidable, such a circular dependency often points to a problem with how you've organized your modules. It's entirely possible that what you currently have as renderengine.h and rmodule.h should be a single header, or perhaps multiple headers but broken along different lines.