Choosing between mpf_class and double at compile time

[Pasquale Tricarico]

Hi,

This is my first post, but I have been using GMP for more than 5
years. I have a fair size C++ project that makes heavy use of
mpf_class, and for performance and testing reasons I would like to
have the possibility to switch between mpf_class and plain double at
compile time. In my code I have:

typedef mpf_class Double;

and then I always refer to Double in my code. This works really well,
but now if I want to switch to double, replacing the above typedef
with the following one is not enough of course:

typedef double Double;

This doesn't work because of all the methods I already call in the
code, such as Double::get_mpf_t(), conversions from/to mpz_class,
printing using gmp_printf("%Ff..."), and probably for a few more
reasons I haven't bumped into yet. Subclassing from double is not
possible as double is not a C++ class but just a type. One approach
could be to fill the code with macro switches such as:

#ifdef USE_GMP
    gmp_printf("%Ff",x.get_mpf_t());
#else
    printf("%f",x);
#endif

But this would severely degrade the code. So I was wondering if anyone
here on the list has a good solution to switch between mpf_class and
double the smart way, staying away from evil macros. Thanks a lot.

Pasquale