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

Guido van Rossum guido at python.org
Wed Nov 5 13:33:56 EST 2003

> So: let's keep it simple and have reversed
> be _exactly_ equivalent to (net of performance, hypothetical anomalous 
> "pseudosequences" doing weird things, & exact error kinds/msgs):
> def reversed(sequence):
>     for x in xrange(len(sequence)-1, -1, -1): yield sequence[x]
> no __reversed__, no complications, "no nuttin'".
> Putting that in the current 2.4 pre-alpha will let us start getting some
> experience with it and see if in the future we want to add refinements
> (always easier to add than to remove...:-) -- either to reverse or to
> other iterator-returning calls (e.g. reverse= optional arguments just
> like in the sort method of lists).

I'd be for that, *if* we also allow as a possible outcome that
reversed() simply doesn't find any use and we take it out before
releasing 2.4b1.

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

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