C macro to enable and disable code features

Question

I\'ve used a code base before that had a macro system for enabling and disabling sections of code. It looked something like the following:

#define IN_USE            


        

Answer 1

Couldn't you just use another group of #ifdefs?

#if defined(WIN32)
    #define FEATURE_A
    #define FEATURE_B
#elif defined (OSX)
    #define FEATURE_C
#endif

// ...

#if defined(FEATURE_A)
    do_a();
#endif

etc.