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

Just don't define it if it is not in use

#if defined( WIN32 )
    #define FEATURE_A       
    #define FEATURE_B       
#else if defined( OSX )
    #define FEATURE_C      
#else

#endif

Then In you code:

void DoFeatures()
{
#ifdef FEATURE_A
    // Feature A code...
#endif

#ifdef FEATURE_B
    // Feature B code...
#endif

#ifdef FEATURE_C
    // Feature C code...
#endif

#ifdef FEATURE_D // Compile error since FEATURE_D was never defined
    // Feature D code...
#endif
}