knowing from where .h was included

Projects Programming
2 
[code]I doubt there's anything predefined, but there's nothing to stop you putting a #define immediately before the #include in your sketch and checking for that.

sketch:
[code]
#define USE_EXTRA_STUFF
#include <myLibrary.h>

myLibrary.h:
[/code]
#ifdef USE_EXTRA_STUFF
...
#endif
[/code]