[Distutils] Python packaging + conditional use of C library shipped with the package

[zooko]

On Mon, Jul 08, 2013 at 01:01:25PM +0200, Laurent Gautier wrote:
> Hi,
> 
> I would like to make a package that is able to use a system's given
> C-library if found, or compile its own version shipped with the
> package.

We do something similar in pycryptopp, but instead of automatically testing for
the locally-available C library, we just ask the human to manually pass
"--disable-embedded-cryptopp" if they want it to attempt to link to a library
external to its own bundled one:

https://tahoe-lafs.org/trac/pycryptopp/browser/git/setup.py?annotate=blame&rev=f789ed951b49b33e7cc49d16fdc8b398f7ec7223

> - Is there a distutils/distribute facility to help test for the
> presence (and version) of a C library, or do I have to roll my own
> system ?

If you succeed at this, I'd like to know how you did it! Maybe we could do
something similar for pycryptopp.

> - When having the source for a C library shipping with a package, is
> there a way to get distutils/distribute compile it, and get it seen
> by Python at runtime (so I can just use ctypes, or cffi, and even C
> extensions in other Python package see the headers and compiled
> libraries) ?

I don't understand the question. This sounds like the normal thing that
distutils has always done for modules made up of compiled C code.

By the way, if I were starting pycryptopp today I would use cffi. (And I would
name it "crpyto".)

Regards,

Zooko