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[3.13] gh-126676: Expand argparse docs for type=bool with warning and alternatives (GH-146435) #148049

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savannahostrowski merged 1 commit into from
Apr 3, 2026
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[3.13] gh-126676: Expand argparse docs for type=bool with warning and alternatives (GH-146435) #148049

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10 changes: 9 additions & 1 deletion Doc/library/argparse.rst
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Expand Up @@ -1017,7 +1017,15 @@ User defined functions can be used as well:

The :func:`bool` function is not recommended as a type converter. All it does
is convert empty strings to ``False`` and non-empty strings to ``True``.
This is usually not what is desired.
This is usually not what is desired::

>>> parser = argparse.ArgumentParser()
>>> _ = parser.add_argument('--verbose', type=bool)
>>> parser.parse_args(['--verbose', 'False'])
Namespace(verbose=True)

See :class:`BooleanOptionalAction` or ``action='store_true'`` for common
alternatives.

In general, the ``type`` keyword is a convenience that should only be used for
simple conversions that can only raise one of the three supported exceptions.
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Documentation/2026-03-25-00-00-00.gh-issue-126676.052336.rst
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@@ -0,0 +1,2 @@
Expand :mod:`argparse` documentation for ``type=bool`` with a demonstration
of the surprising behavior and pointers to common alternatives.
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