66 lines
2.5 KiB
Python
66 lines
2.5 KiB
Python
# -*- coding: utf-8 -*-
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# GNU Guix --- Functional package management for GNU
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# Copyright © 2021 Maxim Cournoyer <maxim.cournoyer@gmail.com>
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#
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# This file is part of GNU Guix.
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#
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# GNU Guix is free software; you can redistribute it and/or modify it
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# under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 3 of the License, or (at
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# your option) any later version.
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#
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# GNU Guix is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
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import os
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import site
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import sys
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# Commentary:
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#
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# Site-specific customization for Guix.
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#
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# The program below honors the GUIX_PYTHONPATH environment variable to
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# discover Python packages. File names appearing in this variable that match
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# a predefined versioned installation prefix are added to the sys.path. To be
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# considered, a Python package must be installed under the
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# 'lib/pythonX.Y/site-packages' directory, where X and Y are the major and
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# minor version numbers of the Python interpreter.
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#
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# Code:
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major_minor = '{}.{}'.format(*sys.version_info)
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site_packages_prefix = os.path.join(
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'lib', 'python' + major_minor, 'site-packages')
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python_site = os.path.join(sys.prefix, site_packages_prefix)
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try:
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all_sites_raw = os.environ['GUIX_PYTHONPATH'].split(os.path.pathsep)
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except KeyError:
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all_sites_raw = []
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# Normalize paths, otherwise a trailing slash would cause it to not match.
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all_sites_norm = [os.path.normpath(p) for p in all_sites_raw]
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matching_sites = [p for p in all_sites_norm
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if p.endswith(site_packages_prefix)]
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if matching_sites:
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# Deduplicate the entries, append them to sys.path, and handle any
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# .pth files they contain.
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for s in matching_sites:
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site.addsitedir(s)
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# Move the entries that were appended to sys.path in front of
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# Python's own site-packages directory. This enables Guix
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# packages to override Python's bundled packages, such as 'pip'.
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python_site_index = sys.path.index(python_site)
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new_site_start_index = sys.path.index(matching_sites[0])
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if python_site_index < new_site_start_index:
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sys.path = (sys.path[:python_site_index]
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+ sys.path[new_site_start_index:]
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+ sys.path[python_site_index:new_site_start_index])
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