[Python-Dev] xrange identity crisis

Guido van Rossum guido@python.org
Tue, 04 Jun 2002 17:12:45 -0400

> On Tue, Jun 04, 2002 at 04:08:08PM -0400, Oren Tirosh wrote:
> > It seems that the xrange object in the current CVS can't make up its mind 
> > whether it's an iterator or an iterable:
> In 2.2, xrange had no "next" method, so it got wrapped by a generic
> iterator object.  It was desirable for performance to have xrange also
> act as an iterator.

This seems to propagate the confusion.  To avoid being wrapped by a
generic iterator object, you need to define an __iter__ method, not a
next method.

The current xrange code (from SF patch #551410) uses the xrange object
as both an iterator and iterable, and has an extra flag to make things
work right when the same object is iterated over more than once.
Without doing more of a review, I can only say that I'm a but
uncomfortable with that approach.  Something like the more recent code
that Raymond H added to listobject.c to add a custom iterator makes
more sense.  But perhaps it is defensible.

--Guido van Rossum (home page: http://www.python.org/~guido/)