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71 lines
2.8 KiB
71 lines
2.8 KiB
5 years ago
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Title: Python 3.7 to become the default target
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Author: Michał Górny <mgorny@gentoo.org>
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Posted: 2020-04-22
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Revision: 1
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News-Item-Format: 2.0
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Display-If-Installed: dev-lang/python:3.6
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Display-If-Installed: dev-lang/python:3.7
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On 2020-05-06 (or later), Python 3.7 will replace Python 3.6 as one
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of the default Python targets for Gentoo systems. The new default
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values will be:
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PYTHON_TARGETS="python2_7 python3_7"
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PYTHON_SINGLE_TARGET="python3_7"
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If you have not overriden these variables on your system, then your
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package manager will switch to the new targets immediately. In order
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to avoid dependency conflicts, please clean stray packages up
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and rebuild/upgrade all packages with USE flag changes after the change,
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e.g.:
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emerge --depclean
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emerge -1vUD @world
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emerge --depclean
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Please note that during the system upgrade some of the package
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dependencies may temporarily become missing. While this should not
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affect programs that are already fully loaded, it may cause ImportErrors
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when starting Python scripts or loading additional modules (only scripts
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running Python 3.6 are affected).
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In order to improve stability of the upgrade, you may choose to
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temporarily enable both targets, i.e. set in /etc/portage/package.use
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or its equivalent:
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*/* PYTHON_TARGETS: python3_6 python3_7
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*/* PYTHON_SINGLE_TARGET: -* python3_6
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This will cause the dependencies to include both Python 3.6 and 3.7
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support whenever possible, throughout the next system upgrade. Once all
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packages are updated, you can restart your scripts, remove the setting
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and start another upgrade in order to cleanly remove Python 3.6.
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There are still some Gentoo packages that do not support Python 3.7.
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We will be pushing updates to these packages as time permits. However,
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some of them will probably be removed instead.
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If you would like to postpone the switch to Python 3.7, you can copy
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the current value of PYTHON_TARGETS and/or PYTHON_SINGLE_TARGET
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to /etc/portage/package.use or its equivalent:
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*/* PYTHON_TARGETS: -python3_7 python3_6
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*/* PYTHON_SINGLE_TARGET: -* python3_6
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If you would like to migrate your systems earlier, you can do
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the opposite. Note that if you are running ~arch, you may want to go
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straight for Python 3.8 at this point.
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Please note that this switch is long overdue. Python 3.6 is no longer
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receiving bug fixes. Its planned end-of-life is 2021-12-23 but we will
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probably remove it earlier than that. [1]
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All above snippets assume using package.use to control USE flags.
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If you still have make.conf entries for these targets, you need
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to remove them. While using make.conf is possible, it is strongly
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discouraged as it does not respect package defaults. The latter
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can help you keep some of Python 3.6 packages without the need to
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explicitly toggle flags per-package.
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[1] https://devguide.python.org/#status-of-python-branches
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