[Numpy-discussion] Proposal: stop supporting 'setup.py install'; start requiring 'pip install .' instead

[Ralf Gommers]

On Thu, Oct 29, 2015 at 12:28 AM, Sandro Tosi <morph at debian.org> wrote:

> please, pretty please, do not disable setup.py install or at least
> keep providing a way for distribution (Debian in this case) to be able
> to build/install numpy in a temporary location for packaging reasons.
> pip is not the solution for us
>

``python setup.py install --force`` would still work. Would that be OK then?

Ralf


> On Tue, Oct 27, 2015 at 12:31 AM, Nathaniel Smith <njs at 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 .
> >
> > (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 at scipy.org
> > https://mail.scipy.org/mailman/listinfo/numpy-discussion
>
>
>
> --
> Sandro Tosi (aka morph, morpheus, matrixhasu)
> My website: http://matrixhasu.altervista.org/
> Me at Debian: http://wiki.debian.org/SandroTosi
> _______________________________________________
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>
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