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Code Issues Projects Releases Packages Wiki Activity Actions 18

[3.5] bpo-29692: contextlib.contextmanager may incorrectly unchain RuntimeError (GH-949) (#1107)

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contextlib._GeneratorContextManager.__exit__ includes a special case to deal with
PEP 479 RuntimeErrors created when `StopIteration` is thrown into the context
manager body.

Previously this check was too permissive, and undid one level of chaining on *all*
RuntimeError instances, not just those that wrapped a StopIteration instance.
(cherry picked from commit 00c75e9a45)
This commit is contained in:
Mariatta 2017-04-13 03:14:53 -07:00 • committed by GitHub
parent c0f4240fac
commit 4d015a40a7
3 changed files with 32 additions and 6 deletions
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12
Lib/contextlib.py
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@ -65,7 +65,7 @@ class _GeneratorContextManager(ContextDecorator):
try:
next(self.gen)
except StopIteration:
return
return False
else:
raise RuntimeError("generator didn't stop")
else:
@ -87,7 +87,7 @@ class _GeneratorContextManager(ContextDecorator):
# Likewise, avoid suppressing if a StopIteration exception
# was passed to throw() and later wrapped into a RuntimeError
# (see PEP 479).
if exc.__cause__ is value:
if type is StopIteration and exc.__cause__ is value:
return False
raise
except:
@ -98,10 +98,10 @@ class _GeneratorContextManager(ContextDecorator):
# fixes the impedance mismatch between the throw() protocol
# and the __exit__() protocol.
#
if sys.exc_info()[1] is not value:
raise
else:
raise RuntimeError("generator didn't stop after throw()")
if sys.exc_info()[1] is value:
return False
raise
raise RuntimeError("generator didn't stop after throw()")
def contextmanager(func):