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

Guido van Rossum guido at python.org
Wed Nov 5 18:08:42 EST 2003

> Unless some _opportune_ (i.e., truly good:-) use case of "naturally 
> reversible nonsequence" (doubly linked list...?-) arises (and the
> __reversed__ idea can inserted then -- just as it could be removed
> if reversed started out with it -- as long as we do it before the beta)
> reversed with or without __reversed__ seem anyway fine to me --
> arguments being so finely balanced on both sides.

It's more effort to add something later than to remove it (since
there's always *someone* who's already dependent on it), so I see the
argument about adding __reversed__ far from balanced.  I see at most a
5% chance that reversed() would be removed before 2.3b1.  If we add
__reversed__ now I doubt that we'll remove it (assuming reversed()
stays), but I still am unconvinced of the need (and I *am* convinced
of the danger).


- I am +1 on adding reversed() provisionally
- I am -1 on adding __reversed__ at the same time

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

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