Need mechanism to pass defines to library cpp files

bperrybap:
Libraries are not slaves to the user of the library.
The library code is compiled separately and the behavior you are seeing is
the expected behavior. This is how libraries work.

Yes, and if the Arduino environment was actually using libraries I would understand that I would have to use a different method to get around the problem, for instance letting a define specify which vesion of the library to link into the code; however, as you point out below, the Arduino libaries are not really libraries, but module of code that get included in the compile process.

As such something simply like would be nice.

#define ENTROPY_FLOAT
#include <Entropy.h>

bperrybap:
The Arduino build methodology is not all that smart and does not save things like the compiled libraries
for re-use across different sketches. However, in the Arduno environment, even though the libraries
are not being saved for other sketches to use, the libraries are still actual libraries and
since a library is a separate entity from the code that uses it, there is no way to do what you are wanting.

--- bill