[issue13274] heapq pure python version uses islice without guarding for negative counts

2011-10-27 Thread Ronny Pfannschmidt 

New submission from Ronny Pfannschmidt :

the problem manifests when calling with negative counts

when the c versions are used, a empty list is returned,
however if the pure python version is called islice errors out

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components: Library (Lib)
messages: 146483
nosy: Ronny.Pfannschmidt
priority: normal
severity: normal
status: open
title: heapq pure python version uses islice without guarding for negative 
counts
type: behavior
versions: Python 2.6, Python 2.7, Python 3.1, Python 3.2, Python 3.3, Python 3.4

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[issue13274] heapq pure python version uses islice without guarding for negative counts

2011-10-27 Thread Petri Lehtinen 

Changes by Petri Lehtinen :


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nosy: +petri.lehtinen

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[issue13274] heapq pure python version uses islice without guarding for negative counts

2011-10-27 Thread Benjamin Peterson 

Changes by Benjamin Peterson :


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nosy: +rhettinger

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[issue13274] heapq pure python version uses islice without guarding for negative counts

2011-10-27 Thread Éric Araujo 

Changes by Éric Araujo :


--
stage:  -> test needed
versions:  -Python 2.6, Python 3.1, Python 3.4

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[issue13274] heapq pure python version uses islice without guarding for negative counts

2011-10-27 Thread Raymond Hettinger 

Raymond Hettinger  added the comment:

The behavior is undefined for negative inputs, so implementations are free to 
the most expedient choices.

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priority: normal -> low

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[issue13274] heapq pure python version uses islice without guarding for negative counts

2011-10-29 Thread Ronny Pfannschmidt 

Ronny Pfannschmidt  added the comment:

however some basic consistency between the cpython and pure python versions 
within the stdlib would be nice

since it basically implicitly breaks unaware code on non cpython

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[issue13274] heapq pure python version uses islice without guarding for negative counts

2011-10-29 Thread Alex Gaynor 

Changes by Alex Gaynor :


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nosy: +alex

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[issue13274] heapq pure python version uses islice without guarding for negative counts

2011-10-29 Thread Raymond Hettinger 

Changes by Raymond Hettinger :


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resolution:  -> invalid
status: open -> closed

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[issue13274] heapq pure python version uses islice without guarding for negative counts

2011-10-30 Thread Roundup Robot 

Roundup Robot  added the comment:

New changeset 57f73b0f921c by Raymond Hettinger in branch '2.7':
Issue 13274:  Make the pure python code for heapq more closely match the C 
implementation for an undefined corner case.
http://hg.python.org/cpython/rev/57f73b0f921c

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nosy: +python-dev

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[issue13274] heapq pure python version uses islice without guarding for negative counts

2011-10-30 Thread Roundup Robot 

Roundup Robot  added the comment:

New changeset 155e57a449b5 by Raymond Hettinger in branch '3.2':
Issue 13274:  Make the pure python code for heapq more closely match the C 
implementation for an undefined corner case.
http://hg.python.org/cpython/rev/155e57a449b5

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[issue13274] heapq pure python version uses islice without guarding for negative counts

2011-10-30 Thread Raymond Hettinger 

Raymond Hettinger  added the comment:

I went ahead an added the guards to the pure python code.

Still disagree with your assertion that non-cpython implementations were 
somehow broken when an undefined behavior was implemented in a different way -- 
nsmallest() and nlargest() have no guaranteed meaning for negative numbers.

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