Re: porting to GNUstep from OSX

[Nicola Pero]

> Maybe just some #ifndef's, combined with -D's in the GNUMakefile would
> be enough? (I.e., #ifndef GNUSTEP #include <objc/runtime.h> #endif)

gnustep-make automatically adds -DGNUSTEP on the command line when 
compiling for GNUstep.

So what I do, and what I guess most people are doing, is 

#ifndef GNUSTEP
 /* Apple specific code */
#else
 /* GNUstep specific code */
#endif

You don't need any autoconf or scripting, this should always work: if you
compile GNUstep code using GNUstep, GNUstep is going to be defined; if you
compile for Apple (using GNUstep or PBX), GNUstep is not going to be
defined.