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bpo-34067: Include a more easily understood example for nullcontext (GH-8158)

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Include a more easily understood example for nullcontext
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Daniel Porteous 2018-07-09 06:49:29 -07:00 • committed by Nick Coghlan
parent 3f4d90d4d7
commit c287545d62
1 changed files with 13 additions and 1 deletions
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14
Doc/library/contextlib.rst
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@ -152,10 +152,22 @@ Functions and classes provided:
.. function:: nullcontext(enter_result=None)
Return a context manager that returns enter_result from ``__enter__``, but
Return a context manager that returns *enter_result* from ``__enter__``, but
otherwise does nothing. It is intended to be used as a stand-in for an
optional context manager, for example::
def myfunction(arg, ignore_exceptions=False):
if ignore_exceptions:
# Use suppress to ignore all exceptions.
cm = contextlib.suppress(Exception)
else:
# Do not ignore any exceptions, cm has no effect.
cm = contextlib.nullcontext()
with cm:
# Do something
An example using *enter_result*::
def process_file(file_or_path):
if isinstance(file_or_path, str):
# If string, open file