On Fri, Aug 24, 2007 at 09:52:16AM -0400, Kent Johnson wrote: Kent and Alan -
Thanks for encouraging me to do a little reading and experimenting. I thought xrange() returned an iterator. I was wrong. Actually xrange() returns an xrange object which, according to the docs, is "an opaque sequence". Small points I suppose, but ... There are some differences between an xrange object and an iterator: - an xrange object can be used multiple times to produce the sequence. An iterator is exhausted after it has produced its sequence. At least, thats what the docs seem to say, although, I suppose, it depends on the implementation of the individual iterator. See http://docs.python.org/lib/typeiter.html. - an xrange object is index-able; iterators are not. Here is the relavant part from the docs: xrange([start,] stop[, step]) This function is very similar to range(), but returns an `xrange object'' instead of a list. This is an opaque sequence type which yields the same values as the corresponding list, without actually storing them all simultaneously. The advantage of xrange() over range() is minimal (since xrange() still has to create the values when asked for them) except when a very large range is used on a memory-starved machine or when all of the range's elements are never used (such as when the loop is usually terminated with break). http://docs.python.org/lib/built-in-funcs.html#l2h-80 Dave -- Dave Kuhlman http://www.rexx.com/~dkuhlman _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
