Make virtualenv use pythonFull, not python

[domenkozar]

See https://github.com/AndersonTorres/nixpkgs/commit/d6feeeaab18cdc9d9942aec8c890f9c8799fa382

[Profpatsch]

(triage) @domenkozar is that solved yet?

[domenkozar]

Nope.

[FRidh]

I never really use virtualenv so I got curious what the issues really are about.

nix-shell -p python35Packages.virtuallenv python35Packages.toolz

[nix-shell:] virtualenv testenv
Using base prefix '/nix/store/ln2cn6g6rf116vaq1fgngaqzpzfq495x-python3-3.5.1'
New python executable in testenv/bin/python3.5m
Also creating executable in testenv/bin/python
Installing setuptools, pip, wheel...done.

[nix-shell:] source test/bin/activate

(testenv)[nix-shell:] python3 -c "import toolz; print(toolz.__version__)"
0.7.4

Clearly, the testenv is not entirely separated from the nix-shell and it's easy to understand why: we've added the package to $PYTHONPATH.

The question is now whether this is an issue. To me it seems more like a feature; nix-shell can already be used to obtain isolation. This gives us instead the possibility to add already packaged packages to an environment, although, of course, this won't work with a requirements.txt or so.

To get back to the issue here. We can use pythonFull, e.g. by just adding all the modules as propagatedBuildInputs to pythonPackages.virtualenv. It seems like an easy fix to me. What do you say?

[domenkozar]

The issue is mostly about UX. python doesn't have readline or sqlite3, which is very annoying in virtualenv. I've been thinking we'd just include both by default since they're light and convenient.

[Profpatsch]

I’d love that!

[FRidh]

Since #19309 we don't have separate modules anymore except tkinter, which is like a 'normal' Python package: pythonPackages.tkinter.

I will soon write some docs on how virtualenv can be used with Nix and what to be wary of.