On Tue, Oct 27, 2015 at 12:31 AM, Nathaniel Smith <n...@pobox.com> wrote:
> Hi all, > > Apparently it is not well known that if you have a Python project > source tree (e.g., a numpy checkout), then the correct way to install > it is NOT to type > > python setup.py install # bad and broken! > > but rather to type > > pip install . > > FWIW, I don't see any mention of this in the numpy docs, but I do see a lot of instructions involving `setup.py build` and `setup.py install`. See, for example, INSTALL.txt. Also see http://docs.scipy.org/doc/numpy/user/install.html#building-from-source So I guess it is not surprising that it is not well known. Warren > (I.e., pip install isn't just for packages on pypi -- you can also > pass it the path to an arbitrary source directory or the URL of a > source tarball and it will do its thing. In this case "install ." > means "install the project in the current directory".) > > These don't quite have identical results -- the main difference is > that the latter makes sure that proper metadata gets installed so that > later on it will be possible to upgrade or uninstall correctly. If you > call setup.py directly, and then later you try to upgrade your > package, then it's entirely possible to end up with a mixture of old > and new versions of the package installed in your PYTHONPATH. (One > common effect is in numpy's case is that we get people sending us > mysterious bug reports about failing tests in files don't even exist > (!) -- because nose is finding tests in files from one version of > numpy and running them against a different version of numpy.) > > But this isn't the only issue -- using pip also avoids a bunch of > weird corner cases in distutils/setuptools. E.g., if setup.py uses > plain distutils, then it turns out this will mangle numpy version > numbers in ways that cause weird horribleness -- see [1] for a bug > report of the form "matplotlib doesn't build anymore" which turned out > to be because of using 'setup.py install' to install numpy. OTOH if > setup.py uses setuptools then you get different weirdnesses, like you > can easily end up with multiple versions of the same library installed > simultaneously. > > And finally, an advantage of getting used to using 'pip install .' now > is that you'll be prepared for the glorious future when we kill > distutils and get rid of setup.py entirely in favor of something less > terrible [2]. > > So a proposal that came out of the discussion in [1] is that we modify > numpy's setup.py now so that if you try running > > python setup.py install > > you get > > Error: Calling 'setup.py install' directly is NOT SUPPORTED! > Instead, do: > > pip install . > > Alternatively, if you want to proceed at your own risk, you > can try 'setup.py install --force-raw-setup.py' > For more information see http://... > > (Other setup.py commands would continue to work as normal.) > > I believe that this would also break both 'easy_install numpy', and > attempts to install numpy via the setup_requires= argument to > setuptools.setup (because setup_requires= implicitly calls > easy_install). install_requires= would *not* be affected, and > setup_requires= would still be fine in cases where numpy was already > installed. > > This would hopefully cut down on the amount of time everyone spends > trying to track down these stupid weird bugs, but it will also require > some adjustment in people's workflows, so... objections? concerns? > > -n > > [1] https://github.com/numpy/numpy/issues/6551 > [2] > https://mail.python.org/pipermail/distutils-sig/2015-October/027360.html > > -- > Nathaniel J. Smith -- http://vorpus.org > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > https://mail.scipy.org/mailman/listinfo/numpy-discussion >
_______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org https://mail.scipy.org/mailman/listinfo/numpy-discussion