How to avoid building C library with my python package?

@rth and @PeterBrittain help me a lot. Here the solution I use:

structure folder :

setup.py
python_package/
    lib/
        libfoo.dylib
        libfoo.dll
    __init__.py
    main.py

setup.py :

from setuptools import setup, dist


class BinaryDistribution(dist.Distribution):
    def is_pure(self):
        return False


setup(
    name='python_package',
    package_data={'python_package': ['lib/libfoo.dylib','lib/libfoo.dll']},
    include_package_data=True,
    distclass=BinaryDistribution,
    packages=['python_package'],
)

main.py :

#!/usr/bin/env python
import platform
from ctypes import CDLL, c_char_p

import pkg_resources

sysname = platform.system()

if sysname == 'Darwin':
    lib_name = "libfoo.dylib"
elif sysname == 'Windows':
    lib_name = "libfoo.dll"
else:
    lib_name = "libfoo.so"
lib_path = pkg_resources.resource_filename('python_package', 'lib/{}'.format(lib_name))
foo = CDLL(lib_path)

bar = foo.bar
bar.restype = c_char_p
bar.argtypes = [c_char_p]

print(bar('hello'))

build wheel :

python setup.py bdist_wheel

It creates a specific plateform wheel rtfdoc-0.0.1-cp34-cp34m-macosx_10_10_x86_64.whl and mac users can do a simple pip install rtfdoc-0.0.1-cp34-cp34m-macosx_10_10_x86_64.whl

This solution is not entirely satisfactory:

• I think I will still need to create a Extension or look at SCons for linux users.
• Update my package will be difficult because of the production of the lib
• I don't know how to manage .dll for 32 bit and 64 bit

Thank you, I learned a lot, and I understand why setup.py in Pillow or Psycopg2 are huge

You can use cibuildwheel to build wheels on Travis CI and/or Appveyor for all kinds of platforms and Python versions. This tool can also deploy your wheels on PyPI or elsewhere.

I prefer my user to install cygwin/mingw32 or cmake and do a pip install mylib [...]. I just want to go further and try to avoid the CMake installation.

As to packaging pre-compiled python modules, see @Peter Brittain's complete answer.

Now, assuming that the user actually has a C compiler installed (whether though cygwin, conda on Windows, or the system one on Linux), and all you want is to avoid the CMake installation, that has no relationship Python packaging.

The question is then how much functionality of CMake you are using and whether the same thing can be accomplished with easier to manage alternatives, see related questions (1), (2) , etc.

Edit: In particular, I was thinking something along the lines of SCons that provides a full build system, but written in Python so it is easier to install in a Python friendly environment than CMake, see full comparison here. A wild guess (I have never used it myself), but since it is a pure python module, you could probably set SCons as a dependency in your setup.py, and fully automate the build of your C code there, so that pip install mylib does everything that's needed. See also, CMake2SCons package that could be useful.

If you don't want the user to build during installation, you have to provide a pre-built binary package, I don't think any other strategy is possible. I've heard good things about py2exe, but I don't use windows so IDK. I've had good experiences with miniconda, but it does require a little extra work to build binary packages from pypi.