#ifndef DONE 

#ifdef TWICE 

// put stuff here to declare 3rd time around 
void g(char* str); 
#define DONE 

#else // TWICE 
#ifdef ONCE 

// put stuff here to declare 2nd time around 
void g(void* str); 
#define TWICE 

#else // ONCE 

// put stuff here to declare 1st time around 
void g(std::string str); 
#define ONCE 

#endif // ONCE 
#endif // TWICE 
#endif // DONE