[Python-3000] optimizing [x]range

[tomer filiba]

i understand there is no much need for using ranges instead of
intervals (a < x < b), but:

1) it's already supported. you CAN use x in range(100), so
why not optimize it? there's no justification to keep it an
O(N) operation (you're not trying to punish anyone :).
it just calls for adding a __contains__ slot to range objects.
the cost is very minimal.

2) ranges are more like set-builder notation, i.e.
evens = {2*n | n in N}
which can be written as
evens = range(0, maxint, 2)
odds = range(1, maxint, 2)
you cannot phrase "x in odds" in "a <= x < b" notation.
sure, just use modulu, but then it just gets ugly.

if range (== xrange) would be a cheap, O(1) operation, there's
not reason to to use it when it suits well.


-tomer

On Jul 29, 12:04 am, "Guido van Rossum" <gu... at python.org> wrote:
> Do we really need another way to spell a <= x < b? Have you got a
> real-world use case in mind for the version with step > 1?
>
> I'm at most lukewarm; I'd be willing to look at a patch to the C code
> in the py3k-struni branch, plus unit tests though.
>
> --Guido
>