[ python-Bugs-1462485 ] StopIteration raised in body of 'with' statement suppressed

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Bugs item #1462485, was opened at 2006-04-01 00:17
Message generated for change (Settings changed) made by pje
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Category: Python Interpreter Core
Group: Python 2.5
>Status: Closed
>Resolution: Fixed
Priority: 7
Submitted By: Tim Delaney (tcdelaney)
>Assigned to: Phillip J. Eby (pje)
Summary: StopIteration raised in body of 'with' statement suppressed

Initial Comment:
Given:

@contextmanager
def gen():
    print '__enter__'

    try:
        yield
    finally:
        print '__exit__'

with gen():
    raise StopIteration('body')


running the above results in:

__enter__
__exit__


I would have expected instead

__enter__
__exit__
Traceback (most recent call last):
  File "test25.py", line 53, in <module>
    raise StopIteration('body')
StopIteration: body


Note that doing:

with gen():
    raise GeneratorExit('body')

does the expected thing:

__enter__
__exit__
Traceback (most recent call last):
  File "test25.py", line 53, in <module>
    raise GeneratorExit('body')
GeneratorExit: body

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>Comment By: Phillip J. Eby (pje)
Date: 2006-04-03 20:06

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This looks good, although the second GeneratorExit test
looks redundant.  I went ahead and checked it in, however,
on the theory that more tests are better than fewer.  :)


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Comment By: Tim Delaney (tcdelaney)
Date: 2006-04-02 02:42

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Attached diffs to test_with.py which adds tests for raising StopIteration (and GeneratorExit) from the body of a with-statement where the context manager is either a generator, or a class instance.

I think the correct behaviour is to return False from GeneratorContextManager.__exit__ if the thrown exception is a StopIteration, and the exact same instance is raised from self.gen.throw(). Diffs for this also attached.

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Comment By: Georg Brandl (gbrandl)
Date: 2006-04-01 07:02

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Nick, I can't tell whether this is intentional without
rereading the specs. Can you?

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Comment By: Tim Delaney (tcdelaney)
Date: 2006-04-01 00:19

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Attached code and results.

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