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

[Nick Coghlan]

https://github.com/python/cpython/commit/c287545d62edf1a1ee65727d3c57befa8c99c13a
commit: c287545d62edf1a1ee65727d3c57befa8c99c13a
branch: master
author: Daniel Porteous <danielporteous1 at gmail.com>
committer: Nick Coghlan <ncoghlan at gmail.com>
date: 2018-07-09T23:49:29+10:00
summary:

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

Include a more easily understood example for nullcontext

files:
M Doc/library/contextlib.rst

diff --git a/Doc/library/contextlib.rst b/Doc/library/contextlib.rst
index 54d3a8e4296b..0b1f4f77dcc8 100644
--- a/Doc/library/contextlib.rst
+++ b/Doc/library/contextlib.rst
@@ -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