Windows build comments

[casevh]

@skirpichev @oscarbenjamin

Some comments on separating GMP, MPFR, and MPC files from gmpy2. This is based on the current code and has only been tested on Windows.

Current state has the [gmp,mpfr,mpc] .h and .lib files installed in gmpy2/gmpy2 and the DLLs are installed in gmpy2.libs. I tried to create a new gmpy2*.pyd file using those installed libraries. It is much easier if the .h and .lib files are installed in gmpy2.libs.

I moved the .h and .lib files on an installed installation and I copied the src/* to a different location in the filesystem. The setup file below is sufficient to compile a new gmpy2*.pyd file. Since my immediate need is to quickly compile and test, I just replaced the previously installed gmpy2*.pyd file with the new one and it worked.

Here is the modified setup.py file. I cut it down to the bare minimum.

from setuptools import Extension, setup
import sys
import os
import platform
import gmpy2

gmpy2_packagedir = os.path.dirname(gmpy2.__file__) + '.libs'

gmpy_ext = [
    Extension("gmpy2.gmpy2",
	      sources=["gmpy2.c"],
              include_dirs=sys.path + [gmpy2_packagedir],
	      library_dirs=sys.path + [gmpy2_packagedir],
              libraries=['mpc','mpfr','gmp'],
              extra_compile_args= ["/DSHARED=1"],
             )
           ]

setup (
       ext_modules = gmpy_ext
)

And the contents of gmpy2.libs are:

gmp.h
gmp.lib
libgmp-10.dll
mpfr.h
mpfr.lib
libmpfr-6.dll
mpc.h
mpc.lib
libmpc-3.dll
libgcc_s_seh-1.dll
libwinpthread-1.dll

Would the following strategy work for bundling the GMP, MPFR, MPC libraries? Names can easily changed.

1. Create "gmpy2libs_vN" for each version of the set of libraries. N is incremented for each new version.
2. gmpy2libs_vN contains the libraries and just enough C code to allow "import gmpy2libs_vN".
3. Users would need to import gmpy2libs_vN before loading their extension.
4. gmpy2libs_vN could contain support functions to assist detecting versions etc.

I don't understand Python packaging requirements to know if this would work or not.