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gh-110722: Add PYTHON_PRESITE to import a module before site.py is run #110769

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Merged
ambv merged 10 commits into from
Oct 14, 2023
Merged

gh-110722: Add PYTHON_PRESITE to import a module before site.py is run #110769

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3daa65a
gh-110722: Add PYTHON_PRESITE=package.module to import a module befor…
ambv Oct 12, 2023
1ef282b
Add Blurb and fix a refleak before anybody notices
ambv Oct 12, 2023
8a201b4
Fix versionadded
ambv Oct 12, 2023
f192e38
Merge branch 'main' into gh-110722-presite
ambv Oct 13, 2023
b89548d
Add test, refine docs, add whatsnew, separate run_presite in pylifecy…
ambv Oct 13, 2023
ebcc373
PEP 7
ambv Oct 13, 2023
bebb594
Only define the static function --with-pydebug
ambv Oct 13, 2023
08679d8
Fix visual indentation
ambv Oct 13, 2023
3d3f5d3
Mention PYTHON_PRESITE needs a pydebug build
ambv Oct 13, 2023
2e1d180
Address Victor's nits
ambv Oct 14, 2023
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Address Victor's nits
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@ambv
ambv committed Oct 14, 2023
commit 2e1d1805b5302ad3529d43b08271ae5de8649be2
20 changes: 13 additions & 7 deletions Doc/using/cmdline.rst
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Expand Up @@ -553,10 +553,11 @@ Miscellaneous options
container system. See also :envvar:`PYTHON_CPU_COUNT`.
If *n* is ``default``, nothing is overridden.
* :samp:`-X presite={package.module}` specifies a module that should be
imported before ``site.py`` is executed and before the :mod:`__main__`
module exists. Therefore, the imported module isn't :mod:`__main__`.
Python needs to be :ref:`built in debug mode <debug-build>` for this
option to exist. See also :envvar:`PYTHON_PRESITE`.
imported before the :mod:`site` module is executed and before the
:mod:`__main__` module exists. Therefore, the imported module isn't
:mod:`__main__`. This can be used to execute code early during Python
initialization. Python needs to be :ref:`built in debug mode <debug-build>`
for this option to exist. See also :envvar:`PYTHON_PRESITE`.

It also allows passing arbitrary values and retrieving them through the
:data:`sys._xoptions` dictionary.
Expand Down Expand Up @@ -1113,9 +1114,14 @@ Debug-mode variables
.. envvar:: PYTHON_PRESITE
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If this variable is set to a module, that module will be imported
early in the interpreter lifecycle, before ``site.py`` is executed,
and before the :mod:`__main__` module is created. Therefore, the
imported module is not treated as :mod:`__main__`.
early in the interpreter lifecycle, before the :mod:`site` module is
executed, and before the :mod:`__main__` module is created.
Therefore, the imported module is not treated as :mod:`__main__`.

This can be used to execute code early during Python initialization.

To import a submodule, use ``package.module`` as the value, like in
an import statement.

See also the :option:`-X presite <-X>` command-line option,
which takes precedence over this variable.
Expand Down