nixpkgs/pkgs/development/interpreters/python/sitecustomize.py
Frederik Rietdijk 46409b5c32 Python: add sitecustomize.py, listen to NIX_PYTHONPATH
This commit adds a Nix-specific module that recursively adds paths that
are on `NIX_PYTHONPATH` to `sys.path`. In order to process possible
`.pth` files `site.addsitedir` is used.

The paths listed in `PYTHONPATH` are added to `sys.path` afterwards, but
they will be added before the entries we add here and thus take
precedence.

The reason for adding support for this environment variable is that we
can set it in a wrapper without breaking support for `PYTHONPATH`.
2019-07-13 09:37:33 +02:00

19 lines
657 B
Python

"""
This is a Nix-specific module for discovering modules built with Nix.
The module recursively adds paths that are on `NIX_PYTHONPATH` to `sys.path`. In
order to process possible `.pth` files `site.addsitedir` is used.
The paths listed in `PYTHONPATH` are added to `sys.path` afterwards, but they
will be added before the entries we add here and thus take precedence.
Note the `NIX_PYTHONPATH` environment variable is unset in order to prevent leakage.
"""
import site
import os
import functools
paths = os.environ.pop('NIX_PYTHONPATH', None)
if paths:
functools.reduce(lambda k, p: site.addsitedir(p, k), paths.split(':'), site._init_pathinfo())