Re: [PATCH] import: pypi: Detect inputs.

[Cyril Roelandt]

On 06/18/2015 12:45 PM, Amirouche Boubekki wrote:
> Héllo,
> 

Hey,

> 
> If I'm not mistaken this patch relies only on the presence of 
> requirements.txt. This is not a required file in python packaging. 
> otherwise said, we miss a lot using this method. I think the best way to 
> do that would be to:
> 

Indeed, requirements.txt is not required. Note that if this file does
not exist, "guix import pypi" will not fail, so this patch should not be
breaking anything.

> - download the package and extract it
> - create an environment (#)
> - create a virtual env with access to system site package of the 
> environment (#)
> - enter the venv and install the package
> - use `pip freeze -l` to retrieve the full set of dependencies
> 

That seems nice, but:

1) I would like to be able to determine whether we have the "right"
version of all the dependencies in the current list of packages (if
requirements.txt specifies "foobar>=2.0" and we only have python-foo-1.0
in Guix, the user should be told that python-foo should be upgraded),
and pip freeze will just give you "pinned" versions (foo==2.0);
2) "pip freeze" will list everything that is installed in the virtual
environment, including the dependencies of the actual dependencies, and
we do not want that.

> If it fails (because of missing system dependencies) fallback to parse 
> setup.py (with guile-log?) and plain requirements.txt. It would be nice 
> to allow to drop to guix environment (#) when the first option fails to 
> inspect and install missing system dependencies manually.
> 

I really do not want to parse setup.py, because you can put any Python
code you want in there, so parsing it properly would require a Python
parser, and an AI that can determine what the code is meant to do. That
might be a bit too complex.

WDYT?

Cyril.