PEP 260 – Simplify xrange()
- guido at python.org (Guido van Rossum)
- Standards Track
This PEP proposes to strip the
xrange() object from some rarely
used behavior like
xrange() function has one idiomatic use:
for i in xrange(...): ...
xrange() object has a bunch of rarely used behaviors
that attempt to make it more sequence-like. These are so rarely
used that historically they have has serious bugs (e.g. off-by-one
errors) that went undetected for several releases.
I claim that it’s better to drop these unused features. This will simplify the implementation, testing, and documentation, and reduce maintenance and code size.
I propose to strip the
xrange() object to the bare minimum. The
only retained sequence behaviors are
In particular, these behaviors will be dropped:
i in x(containment test)
I also propose to change the signature of the
PyRange_New() C API
to remove the 4th argument (the repetition count).
By implementing a custom iterator type, we could speed up the common use, but this is optional (the default sequence iterator does just fine).
This PEP affects the
xrange() built-in function and the
PyRange_New() C API.
Somebody’s code could be relying on the extended code, and this code would break. However, given that historically bugs in the extended code have gone undetected for so long, it’s unlikely that much code is affected.
For backwards compatibility, the existing functionality will still be present in Python 2.2, but will trigger a warning. A year after Python 2.2 final is released (probably in 2.4) the functionality will be ripped out.
This document has been placed in the public domain.
Last modified: 2017-11-11 19:28:55 GMT