COBJ_INTERFACE_IMPLEMENTATION_MODE causing trouble

[gprossliner]

cobj needs to generate some code for a class implementing an interface, like the methodtable struct. This is currently enabled for an included header, if COBJ_INTERFACE_IMPLEMENTATION_MODE is defined.
This is causing trouble, because one .h file may included other .h files as dependencies, but they are not implemented in the given class.
A solution need to be implemented, that COBJ_INTERFACE_IMPLEMENTATION_MODE is not specified by the user, but that cobj does something like (pseudo-code):

#define COBJ_INTERFACE_IMPLEMENTATION_MODE COBJ_INTERACE_NAME exisits_in COBJ_CLASS_INTERFACES

This would lead to cleaner code anyway, because this symbol defines redundant data.

[gprossliner]

This will go into version 2.

I've tried that many, many, many things to make it work. Also tried some popular PP libraries like CHAOS-PP or BOOST. But the preprocessor seems really not to be able to compare strings (or symbol names).

The requirement: Detect in a macro (that can be used in an #if), if the current value of the COBJ_INTERFACE_NAME symbol is in the COBJ_CLASS_INTERFACES -> COBJ_CLASS_INTERFACE(NAME) X-Macro, like:

// in interface1.h
#define COBJ_INTERFACE_NAME interface1
#include "cobj-interface-generator.h"

// in interface2.h
#define COBJ_INTERFACE_NAME interface2
#include "cobj-interface-generator.h"

// class.h

#define COBJ_CLASS_INTERFACES \
 COBJ_CLASS_INTERFACE(interface1)

#include "interface1.h"
#include "interface2.h"

// cobj-interface-generator.h
#define COBJ_IMPLEMENTS_CURRENT_INTERFACE() <any macro that evaluates to 1 for interface1, and 0 for interface2>
#if COBJ_IMPLEMENTS_CURRENT_INTERFACE()
 // render some code for a class implementing the current interface
#endif
#undef COBJ_INTERFACE_NAME

The solution is not really complicated, but because I was not able to compare names in the preprocessor, there will be a requirement for any interface to #define a numeric id based on a nameing schema, that is used for the compare operation:

// in interface1.h
#define COBJ_INTERFACE_NAME interface1
#define interface1_COBJ_ID 1
#include "cobj-interface-generator.h"

// in interface2.h
#define COBJ_INTERFACE_NAME interface2
#define interface1_COBJ_ID 2
#include "cobj-interface-generator.h"

// cobj-interface-generator.h
#define COBJPVT_GEN_CLASS_INTERFACE_TEMPLATE(GEN_INTERFACE_NAME) \
|| COBJ_PP_CONCAT(GEN_INTERFACE_NAME, _COBJ_ID) == \
COBJ_PP_CONCAT(COBJ_INTERFACE_NAME, _COBJ_ID)

// so when calling the generator COBJPVT_GEN_CLASS_INTERFACE_GENERATOR(), each interface translates to
// || every_implemented_interface_COBJ_ID == current_interface_COBJ_ID

// the "0" is an "dummy or", to render a valid syntax for the single logical or operations
#define COBJ_IMPLEMENTS_CURRENT_INTERFACE() 0 COBJPVT_GEN_CLASS_INTERFACE_GENERATOR()

#if COBJ_IMPLEMENTS_CURRENT_INTERFACE()
// for interface1.h it expands to:  0 || 1==1    TRUE! Render implementation code
// for interface2.h it expands to:  0 || 2==1    FALSE! Don't render implementation code

#endif

It would be great to skipp the _COBJ_ID symbols, and somehow compare the names directly. If someone is aware of a technique please let me know!