[Numpy-discussion] specifying numpy as dependency in your project, install_requires

[Benjamin Root]

On Fri, Sep 21, 2012 at 4:19 PM, Travis Oliphant <travis at continuum.io>wrote:

>
> On Sep 21, 2012, at 3:13 PM, Ralf Gommers wrote:
>
> Hi,
>
> An issue I keep running into is that packages use:
>     install_requires = ["numpy"]
> or
>     install_requires = ['numpy >= 1.6']
>
> in their setup.py. This simply doesn't work a lot of the time. I actually
> filed a bug against patsy for that (
> https://github.com/pydata/patsy/issues/5), but Nathaniel is right that it
> would be better to bring it up on this list.
>
> The problem is that if you use pip, it doesn't detect numpy (may work
> better if you had installed numpy with setuptools) and tries to
> automatically install or upgrade numpy. That won't work if users don't have
> the right compiler. Just as bad would be that it does work, and the user
> didn't want to upgrade for whatever reason.
>
> This isn't just my problem; at Wes' pandas tutorial at EuroScipy I saw
> other people have the exact same problem. My recommendation would be to not
> use install_requires for numpy, but simply do something like this in
> setup.py:
>
>     try:
>         import numpy
>     except ImportError:
>         raise ImportError("my_package requires numpy")
>
> or
>
>     try:
>         from numpy.version import short_version as npversion
>     except ImportError:
>         raise ImportError("my_package requires numpy")
>     if npversion < '1.6':
>        raise ImportError("Numpy version is %s; required is version >= 1.6"
> % npversion)
>
> Any objections, better ideas? Is there a good place to put it in the numpy
> docs somewhere?
>
>
> I agree.   I would recommend against using install requires.
>
> -Travis
>
>
>
Why?  I have personally never had an issue with this.  The only way I could
imagine that this wouldn't work is if numpy was installed via some other
means and there wasn't an entry in the easy-install.pth (or whatever
equivalent pip uses).  If pip is having a problem detecting numpy, then
that is a bug that needs fixing somewhere.

As for packages getting updated unintentionally, easy_install and pip both
require an argument to upgrade any existing packages (I think -U), so I am
not sure how you are running into such a situation.

I have found install_requires to be a powerful feature in my setup.py
scripts, and I have seen no reason to discourage it.  Perhaps I am the only
one?

Ben Root
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