[Python-Dev] Allowing slicing of iterators (original) (raw)

Nick Coghlan ncoghlan at iinet.net.au
Wed Jan 26 09:06:36 CET 2005

Guido van Rossum wrote:

Iterators are for single sequential access. It's a feature that you have to import itertools (or at least that you have to invoke its special operations) -- iterators are not sequences and shouldn't be confused with such.

I agree the semantic difference between an iterable and an iterator is important, but I am unclear on why that needs to translate to a syntactic difference for slicing, when it doesn't translate to such a difference for iteration (despite the major difference in the effect upon the object that is iterated over). Are the semantics of slicing really that much more exact than those for iteration?

Also, would it make a difference if the ability to extract an individual item from an iterator through subscripting was disallowed? (i.e. getting the second item of an iterator being spelt "itr[2:3].next()" instead of "itr[2]")

Regards, Nick.

-- Nick Coghlan | ncoghlan at email.com | Brisbane, Australia

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