Michael Hoffman wrote:

I'm creating a package that uses NumPy to build an extension module. In order to do this, one must call numpy.get_include() like this:

ext_modules = [Extension("_fwd_bwd", ["src/_fwd_bwd.pyx", "src/fwd_bwd.c"], include_dirs=[numpy.get_include()])]

The problem is that if NumPy is not already installed, this will fail. I can't use setup_requires in a simple manner because the function call needs to happen before the call to setup().

The solution of creating another Distribution object to satisfy setup_requires before running setup() suggested in <http://mail.python.org/pipermail/distutils-sig/2006-October/006744.html> is unsatisfactory for the reasons also suggested there--if I do this --help will not work and it also seems a bit clunky.

I was thinking of instead making a subclass of Extension that will call populate include_dirs from a function rather than a list of strings. Is this the best solution?

The below seems to work partially. The problem is that you don't immediately get help when running setup.py --help. It tries to install numpy first, which isn't very friendly. setuptools would also be more friendly if setuptools.dist.fetch_build_egg printed a message that it was about to go off and fetch software much like easy_install does. The first warning I get is "Running from numpy source directory." only after a long delay to download the source. PJE, would you consider adding such a message? My NumpyExtension subclass: """ from setuptools import Extension, setup class NumpyExtension(Extension): def __init__(self, *args, **kwargs): Extension.__init__(self, *args, **kwargs) self._include_dirs = self.include_dirs del self.include_dirs # restore overwritten property # warning: Extension is a classic class so it's not really read-only @property def include_dirs(self): from numpy import get_include return self._include_dirs + [get_include()] ext_modules = [NumpyExtension("_fwd_bwd", ["src/_fwd_bwd.pyx", "src/fwd_bwd.c"])] """ $ python -c "import pkg_resources; print pkg_resources.require('setuptools')" [setuptools 0.6c7 (/usr/lib/python2.5/site-packages/setuptools-0.6c7-py2.5.egg)]