Skip to content

[3.7] bpo-34067: Include a more easily understood example for nullcontext (GH-8158) #8199

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
miss-islington merged 1 commit into from
Jul 9, 2018
Merged

[3.7] bpo-34067: Include a more easily understood example for nullcontext (GH-8158) #8199

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
14 changes: 13 additions & 1 deletion Doc/library/contextlib.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down