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Why doesn't setup_requires work properly for numpy?

I wanted to create a setup.py file that automatically resolves a build-time dependency to numpy (for compiling extensions). My first guess was to use setup_requires and subclass a command class to import the numpy module:

from setuptools import setup, Extension
from distutils.command.build import build as _build

class build(_build):
    def run(self):
        import numpy
        print(numpy.get_include())
        _build.run(self)

setup(
    name='test',
    version='0.0',
    description='something',
    cmdclass={'build':build},
    setup_requires=['numpy'],
)

Now, running python setup.py build successfully compiles numpy but then fails (inside build.run) with:

AttributeError: 'module' object has no attribute 'get_include'

However, if the running the same command again, the command now succeeds (and doesn't need to recompile numpy).

I have tested this on python{2.6,2.7,3.3} with and without virtualenv on pretty recent versions setuptools.

I have seen a workaround using pkg_resources.resource_filename which seems to work just fine, if all we want is the include directory. EDIT: only works on python2!

But still, I am now curious. What caveats does the usage of setup_requires have? What could be the reasons that it doesn't work properly for numpy? For some more simple modules it seems to have no problems.

like image 820
coldfix Avatar asked Feb 06 '14 14:02

coldfix


1 Answers

Figured out, that a proper initialization of the numpy module is prevented by a check for __NUMPY_SETUP__ inside numpy/__init__.py:

if __NUMPY_SETUP__:
    import sys as _sys
    _sys.stderr.write('Running from numpy source directory.\n')
    del _sys
else:
    # import subodules etc. (main branch)

This global state is not reset by setuptools after the installation. The following works:

...
def run(self):
    __builtins__.__NUMPY_SETUP__ = False
    import numpy
    ...
like image 152
coldfix Avatar answered Oct 21 '22 14:10

coldfix