2001-06-26 13:57:11 -04:00
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PEP: 260
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Title: Simplify xrange()
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Version: $Revision$
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Author: guido@python.org (Guido van Rossum)
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2001-08-14 15:16:31 -04:00
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Status: Final
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2001-06-26 13:57:11 -04:00
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Type: Standards Track
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Python-Version: 2.2
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Created: 26-Jun-2001
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Post-History: 26-Jun-2001
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Abstract
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This PEP proposes to strip the xrange() object from some rarely
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used behavior like x[i:j] and x*n.
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Problem
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The xrange() function has one idiomatic use:
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for i in xrange(...): ...
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However, the xrange() object has a bunch of rarely used behaviors
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that attempt to make it more sequence-like. These are so rarely
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used that historically they have has serious bugs (e.g. off-by-one
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errors) that went undetected for several releases.
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I claim that it's better to drop these unused features. This will
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simplify the implementation, testing, and documentation, and
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reduce maintenance and code size.
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Proposed Solution
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I propose to strip the xrange() object to the bare minimum. The
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only retained sequence behaviors are x[i], len(x), and repr(x).
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In particular, these behaviors will be dropped:
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x[i:j] (slicing)
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x*n, n*x (sequence-repeat)
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cmp(x1, x2) (comparisons)
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i in x (containment test)
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x.tolist() method
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x.start, x.stop, x.step attributes
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2001-07-05 10:50:56 -04:00
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I also propose to change the signature of the PyRange_New() C API
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to remove the 4th argument (the repetition count).
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2001-06-26 13:57:11 -04:00
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By implementing a custom iterator type, we could speed up the
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common use, but this is optional (the default sequence iterator
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does just fine).
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Scope
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2001-07-05 10:50:56 -04:00
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This PEP affects the xrange() built-in function and the
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PyRange_New() C API.
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2001-06-26 13:57:11 -04:00
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Risks
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Somebody's code could be relying on the extended code, and this
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code would break. However, given that historically bugs in the
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extended code have gone undetected for so long, it's unlikely that
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much code is affected.
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2001-08-01 14:25:51 -04:00
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Transition
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For backwards compatibility, the existing functionality will still
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be present in Python 2.2, but will trigger a warning. A year
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after Python 2.2 final is released (probably in 2.4) the
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functionality will be ripped out.
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2001-06-26 13:57:11 -04:00
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Copyright
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This document has been placed in the public domain.
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Local Variables:
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mode: indented-text
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indent-tabs-mode: nil
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End:
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