COBJ_IMPLEMENTATION_FILE causing trouble

[gprossliner]

This is similar to #8. The #define COBJ_IMPLEMENTATION_FILE works as long as you don't include any class-header in "another" implementation file. Simply because there is no "another", so cobj will render code for the "another" class.

[gprossliner]

I will solve this similar that it is planed for #8: For the ability to compare, you have to define a "clasname_COBJ_ID" symbol with a unique integer != 0.

// theclass.h
#define COBJ_CLASS_NAME theclass
#define theclass_COBJ_ID 1

#include "cobj-classheader-generator.h"

// otherclass.h
#define COBJ_CLASS_NAME otherclass
#define otherclass_COBJ_ID 2

#include "cobj-classheader-generator.h"

// theclass.c (bug):
#define COBJ_IMPLEMENTATION_FILE 
#include "theclass.h"   // everything ok, we really implement this
#include "otherclass.h // NOK! we just depend on this header, but don't implement it. But how should cobj know?

// theclass.c (planed fix):
#define COBJ_IMPLEMENTATION_FILE(theclass)
#include "theclass.h"   // everything ok, theclass_COBJ_ID == theclass_OBJ_ID => render code
#include "otherclass.h // everything ok, NOT theclass_COBJ_ID == otherclass_OBJ_ID  => don't render code

[gprossliner]

#define COBJ_IMPLEMENTATION_FILE(theclass) is not possible. This would just create an "empty" macro, where the given argument is lost forever.

There are the following alternatives:

#define COBJ_IMPLEMENTATION_FILE theclass // this allows us to eval COBJ_IMPLEMENTATION_FILE

#define COBJ_IMPLEMENTATION_FILE(XYZ(theclass)) // this allows us to use X-Macro as with #8

The first approch seems cleaner, so I'll go this route.