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Now with cleaner explanation of how to keep eselect-python: |
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``` |
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Title: Python preference to follow PYTHON_TARGETS |
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Author: Michał Górny <mgorny@g.o> |
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Posted: 2021-01-24 |
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Revision: 1 |
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News-Item-Format: 2.0 |
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|
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On 2021-02-01 stable users will switch to a new method of updating |
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the preferred Python versions that employs the configuration update |
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mechanism in order to follow PYTHON_TARGETS. We will also deprecate |
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and stop installing app-eselect/eselect-python by default. If you wish |
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to use the newest Python version present in your PYTHON_TARGETS, you |
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only have to accept configuration changes. If you wish to customize |
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the behavior, read on. |
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|
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Since 2017, /usr/bin/python and the related non-versioned symlinks |
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are wrapped through dev-lang/python-exec. The list of preferred Python |
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implementations is stored in /etc/python-exec/python-exec.conf and/or |
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per-program /etc/python-exec/<basename>.conf configuration files. |
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To preserve backwards compatibility, app-eselect/eselect-python remained |
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a wrapper that updated this file. |
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|
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However, this mechanism alone has proven inconvenient to end users who |
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had to update python-exec.conf whenever the default PYTHON_TARGETS |
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changed. Thanks to the fallback logic, this was not a major problem |
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for software installed via Gentoo packages that always ensure that |
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a supported implementation is used. However, users have reported that |
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whenever the preference for /usr/bin/python mismatched their |
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PYTHON_TARGETS, their custom scripts would break due to unsatisfied |
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dependencies. This does not follow the principle of least surprise. |
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|
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For this reason, we have decided to change the default python-exec |
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configuration to match PYTHON_TARGETS by default, in the eclass |
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preference order, that is from the newest CPython version to oldest, |
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with alternative Python implementations coming afterwards. This change |
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will be propagated via the configuration protection mechanism whenever |
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dev-lang/python-exec-conf is installed or rebuilt due to PYTHON_TARGETS |
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changes. This will permit the users to interactively confirm |
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the updates. |
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|
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If the new default is not correct for you, please use your preferred |
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configuration update tool to discard or edit the new configuration file. |
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|
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Furthermore, dev-lang/python will no longer attempt to automatically |
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update the Python interpreter preference, or pull in eselect-python |
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automatically. If you wish to continue using it, please install/record |
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it explicitly to ensure that it is not unmerged, e.g.: |
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|
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emerge -n app-eselect/eselect-python |
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|
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``` |
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|
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|
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-- |
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Best regards, |
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Michał Górny |
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