[ python-Bugs-1242657 ] list(obj) can swallow KeyboardInterrupt

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Bugs item #1242657, was opened at 2005-07-22 01:22
Message generated for change (Comment added) made by stevea_zope
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Category: Python Interpreter Core
Group: None
Status: Closed
Resolution: Fixed
Priority: 5
Submitted By: Steve Alexander (stevea_zope)
Assigned to: Raymond Hettinger (rhettinger)
Summary: list(obj) can swallow KeyboardInterrupt

Initial Comment:
The example below shows that list(f) swallows the
KeyboardInterrupt.

It swallows any other exception too, such as
MemoryError or application-specific ConflictErrors.

I think the "get the length of the object" optimisation
should catch only AttributeError and TypeError.

>>> class F(object):
...     def __iter__(self):
...         yield 23
...     def __len__(self):
...         print "len called.  raising Keyboard
Interrupt."
...         raise KeyboardInterrupt
...
>>> f = F()
>>> list(f)
len called.  raising Keyboard Interrupt.
[23]


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>Comment By: Steve Alexander (stevea_zope)
Date: 2005-09-16 12:02

Message:
Logged In: YES 
user_id=492001

Interestingly, I just saw some code that was causing a
problem in the SchoolTool project.  It had a __len__ method
that used list(self), causing great slowness without this
fix, and a RuntimeError "maximum recursion depth exceeded"
with this fix.

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Comment By: Raymond Hettinger (rhettinger)
Date: 2005-08-21 14:10

Message:
Logged In: YES 
user_id=80475

Okay, fixed in several places.  This little fragment
occurred in a number of places including code listextend(),
map(), zip(), filter(),  and PySequence_Tuple().  



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