[Python-Dev] Re: PEP 322: Reverse Iteration

Andrew P. Lentvorski, Jr. bsder at allcaps.org
Wed Nov 5 19:26:12 EST 2003

On Wed, 5 Nov 2003, Guido van Rossum wrote:

> I'm okay with adding reversed() as a builtin that works for sequences
> only but I'm not okay with adding the __reversed__ protocol.

But, doesn't this effectively take the PEP back to the original proposal
of a sequence method that it drifted away from?

With the restriction to sequences, reversed() is then likely to be
implemented as a thin wrapper around seq.somerevmethod() which could then
return either a new reversed sequence, an iterable, or an iterator
depending upon efficiency, implementation, thread-safety, etc.

Since reversed() is turning out not be generally applicable anyway,
perhaps going back to the original idea of a sequence method would be a
good thing?


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