Need to pass defines to library cpp files during sketch compile

[wandrson]

I am attempting to modify my Entropy library to allow the user to decide if they want to include floating point functions for the library. I placed conditional defines around the relavent code; however, it wouldn't link. I determined that the source level #define was not being passed to the libraries cpp compile, though it was passed to the libraries header file.

My current solution is to require the user to comment/uncomment the header file for the library, but this is cumbersome, and problematic. It would be nice if the compilation for library code included the defines made by the Arduino sketch.

[matthijskooijman]

This is a duplicate of #1734 / #1808

[ricardojlrufino]

I have a tip:
What do you think of working on convention where settings (#define) would be placed in the config.h inside sketch folder?

[cmaglie]

Closing as duplicate of #1734 #1808