PEP: 260 Title: Simplify xrange() Version: $Revision$ Last-Modified: $Date$ Author: guido@python.org (Guido van Rossum) Status: Final Type: Standards Track Content-Type: text/x-rst Created: 26-Jun-2001 Python-Version: 2.2 Post-History: 26-Jun-2001 Abstract ======== This PEP proposes to strip the ``xrange()`` object from some rarely used behavior like ``x[i:j]`` and ``x*n``. Problem ======= The ``xrange()`` function has one idiomatic use:: for i in xrange(...): ... However, the ``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. Proposed Solution ================= I propose to strip the ``xrange()`` object to the bare minimum. The only retained sequence behaviors are ``x[i]``, ``len(x)``, and ``repr(x)``. In particular, these behaviors will be dropped: * ``x[i:j]`` (slicing) * ``x*n``, ``n*x`` (sequence-repeat) * ``cmp(x1, x2)`` (comparisons) * ``i in x`` (containment test) * ``x.tolist()`` method * ``x.start``, ``x.stop``, ``x.step`` attributes 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). Scope ===== This PEP affects the ``xrange()`` built-in function and the ``PyRange_New()`` C API. Risks ===== 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. Transition ========== 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. Copyright ========= This document has been placed in the public domain. .. Local Variables: mode: indented-text indent-tabs-mode: nil End: