Project:Python/PYTHON TARGETS

PYTHON_TARGETS and PYTHON_SINGLE_TARGET are [[Article description::USE_EXPAND variables controlling support for various Python implementations (versions) in packages.]] These essentially control what version of Python the package will reference during and after installation.

Enabling Python implementations

The modern packages (using -r1 suite eclasses) use explicit USE flags aggregated in PYTHON_TARGETS and PYTHON_SINGLE_TARGET USE_EXPAND variables. The variables are defaulted in profiles and can be changed in make.conf. The flags may be adjusted per-package using package.use as well.

The PYTHON_TARGETS variable is used for packages that support enabling more than a single Python implementation. Therefore, the variable may contain any number of implementations.

The PYTHON_SINGLE_TARGET variable is used for packages that are built for a single implementation of choice only. It may contain only a single implementation. Due to technical limitations, the implementation specified as PYTHON_SINGLE_TARGET must also be included in PYTHON_TARGETS for the package in question.

The possible values are listed in the PYTHON_COMPAT column of the Python project's implementations list.

FILE /etc/portage/package.useExamples of PYTHON_TARGETS/PYTHON_SINGLE_TARGET

<syntaxhighlight lang="bash"># Enabling additional implementation in addition to the profile default
*/* PYTHON_TARGETS: python3_7
# Replacing the profile default with specific implementation
*/* PYTHON_SINGLE_TARGET: -python3_6 python3_7
# Build vim for python2.7 instead of the above
# (note: -* in PYTHON_TARGETS is optional but it makes it possible to avoid extraneous deps
app-editors/vim PYTHON_TARGETS: -* python2_7 PYTHON_SINGLE_TARGET: -* python2_7
# Enable all Python implementation for Portage
sys-apps/portage PYTHON_TARGETS: *</syntaxhighlight>

Unmasking non-stable implementation on a stable system

If you'd like to use an implementation that is not stable on your architecture on a stable system, you need to:

Unmask the implementation using /etc/portage/package.accept_keywords,
Unmask the relevant USE flags using /etc/portage/profile/use.stable.mask. This also requires to set /etc/portage/profile to EAPI >= 5.

FILE /etc/portage/package.accept_keywordsUnmasking Python 3.5

dev-lang/python:3.5

FILE /etc/portage/profile/use.stable.maskUnmasking flags for Python 3.5

-python_targets_python3_5
-python_single_target_python3_5

FILE /etc/portage/profile/eapiSetting eapi 5

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