Dead simple setup.py to experiment with setuptools' setup_requires feature

foo.c

#include "numpy/arrayobject.h"

setup.py

from distribute_setup import use_setuptools
use_setuptools()

from setuptools import setup
from setuptools.extension import Extension


class DelayedExtension(Extension, object):
    """
    A distutils Extension subclass where some of its members
    may have delayed computation until reaching the build phase.

    This is so we can, for example, get the Numpy include dirs
    after pip has installed Numpy for us if it wasn't already
    on the system.
    """
    def __init__(self, *args, **kwargs):
        super(DelayedExtension, self).__init__(*args, **kwargs)
        self._finalized = False
        self._hooks = {}

    def add_hook(self, member, func):
        """
        Add a hook to dynamically compute a member.

        Parameters
        ----------
        member : string
            The name of the member

        func : callable
            The function to call to get dynamically-computed values
            for the member.
        """
        self._hooks[member] = func

    def finalize(self):
        self._finalized = True

    class DelayedMember(property):
        def __init__(self, name):
            self._name = name

        def __get__(self, obj, objtype=None):
            result = getattr(obj, '_' + self._name, [])

            if obj._finalized:
                if self._name in obj._hooks:
                    result = obj._hooks[self._name]() + result

            return result

        def __set__(self, obj, value):
            setattr(obj, '_' + self._name, value)

    include_dirs = DelayedMember('include_dirs')


ext = DelayedExtension("foo", ["foo.c"])


distrib = setup(
    name="dependencies",
    ext_modules=[ext],
    setup_requires=["numpy"])