[Distutils] dependencies, pip and non-PyPI-hosted packages

[Carl Meyer]

Hi Ernesto,

On 04/19/2011 12:42 PM, Ernesto Posse wrote:
> Hi I have a couple of packages that I don't want to upload to PyPI
> just yet but they are hosted some other place, and one (project2)
> depends on the other (project1). I've packaged them using the standard
> distutils setup.
> 
> For project1, setup.py contains:
> 
>   setup(name='project1', ..., requires=[], provides=['project1'], ...)
> 
> and for project2, setup.py contains:
> 
>   setup(name='project2', ..., requires=['project1'], provides=['project2'], ...)
> 
> I put them in some host https://my.host.org/repository, but when I run
> 
>   pip install -f https://my.host.org/repository project2
> 
> installs project2 correctly, but it does not install project1.
> 
> So my first question is: is the 'requires' keyword in setup.py
> actually used when installing packages? or it only works for projects
> hosted on PyPI?

The "standard" requires and provides keywords defined in PEP 314 and
accepted by distutils are, AFAIK, not actually used by any existing
tools. They are also deprecated by the newer PEP 345 metadata standard.

(The reason for this, as I understand it, is that those keywords were
defined by PEP 314 to refer to importable module/package names rather
than project names. This makes them almost impossible for an installer
to use, given that we have no global mapping available for translating
an importable module/package name to an installable project name.)

In order to have pip (or any other tool I know of) respect dependencies
specified in setup.py, you need to use setuptools (or the "distribute"
fork) in your setup.py and use its install_requires keyword argument
instead. See
http://peak.telecommunity.com/DevCenter/setuptools#new-and-changed-setup-keywords
for details.

Carl