build the same source twice with different macros

[Nicolas Bock]

Hello list,

I have some functions written in C that take a floating point argument, e.g.

void foos (float x);
void food (double x);

The function bodies are basically identical except of course for the
different floating point types. In order to avoid having to write
redundant code, I see 2 options:

(1) I can use C++ and rewrite the function header as a template.
(2) I can define a macro for the preprocessor that is either defined
as "float" or "double" and then compile the function source twice, the
first time with $CC -DFLOAT=float and the second time with $CC
-DFLOAT=double.

Is option (2) possible within automake without excessive hackery? Is
it advisable? Is there a third option that I might want to consider?

Thanks already for your opinions,

nick