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gh-139452: Clarify redirect_stdout, stderr behavior #139490

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gh-139452: Clarify redirect_stdout, stderr behavior #139490

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gh-139452: Clarify redirect_stdout, stderr behavior
cmaloney Oct 2, 2025
af01958
Add discard/suppress example
cmaloney Oct 3, 2025
976045e
Remove open() reference per issue comment
cmaloney Oct 6, 2025
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11 changes: 7 additions & 4 deletions Doc/library/contextlib.rst
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Expand Up @@ -327,10 +327,12 @@ Functions and classes provided:
.. function:: redirect_stdout(new_target)

Context manager for temporarily redirecting :data:`sys.stdout` to
another file or file-like object.
another :term:`file object`.

This tool adds flexibility to existing functions or classes whose output
is hardwired to stdout.
is hardwired to :data:`sys.stdout`. This does not modify underlying file
objects or file descriptors. It sets the global :data:`sys.stdout` to the
provided value and at context exit sets it to the previous value.

For example, the output of :func:`help` normally is sent to *sys.stdout*.
You can capture that output in a string by redirecting the output to an
Expand Down Expand Up @@ -366,8 +368,9 @@ Functions and classes provided:

.. function:: redirect_stderr(new_target)

Similar to :func:`~contextlib.redirect_stdout` but redirecting
:data:`sys.stderr` to another file or file-like object.
Similar to :func:`~contextlib.redirect_stdout` but redirecting the global
:data:`sys.stderr` to another value, typically a :term:`file object`
returned from :func:`open`.

This context manager is :ref:`reentrant <reentrant-cms>`.

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