[Distutils] Specify missing install-requires dependencies to develop egg?

Jim Fulton jim at zope.com
Fri Aug 26 15:05:42 CEST 2011

On Thu, Aug 25, 2011 at 9:06 PM, Matthew Brett <matthew.brett at gmail.com> wrote:
> Hi,
> We have been working on using buildout with a develop package
> depending on numpy, and ran into trouble because 'numpy' is not
> specified in the package 'install_requires'.
> Specifically, we have something like this:
> [buildout]
> parts =
>    nibabel-target
>    mypy
> [nibabel-target]
> recipe = zc.recipe.egg:develop
> setup = src/nibabel
> [mypy]
> recipe = zc.recipe.egg:script
> eggs =
>    nibabel
> interpreter = py
> 'nibabel' needs to import numpy to install, but does not specify
> 'numpy' in its setup.py install_requires, because pip install of numpy
> is fragile, and we wanted to error early in general for an attempted
> pip install of nibabel, if numpy was not present.
> But of course the script above raises an error for the
> 'nibabel-target' part, because of missing numpy:
> -------------
> RuntimeError: Cannot import package "numpy" - is it installed?
> While:
>  Installing nibabel-target.
> An internal error occurred due to a bug in either zc.buildout or in a
> recipe being used:
> ------------
> What we would very much like to do, is to be able to specify the
> missing install_requires for this package (and for others we are
> thinking of working with), in the recipe - something like:
> [nibabel-target]
> recipe = zc.recipe.egg:develop
> setup = src/nibabel
> install-requires =
>    numpy
> but we couldn't immediately see a way of specifying such a dependency.
>  A quick look at the Develop code in zc/recipe/egg/custom.py
> suggested that there wasn't an easy way to add some needed egg onto
> the path at this point.
> Is there anything we missed that we should have tried?
> If not, what would be the best way to solve our problem?  A modified recipe?

Theoretically, you'd use setup_requires to specify packages needed by setup.
I'm not sure if that works with buildout. I've heard reports that it
does and reports that
it doesn't.

Why does nibabel want numpy at setup time? If it's to get C incluse files, then
you may be out of luck, as it's unlikely that buildout will install
numpy in a way that
will give nibabel what it wants.


Jim Fulton

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