On 2005-01-15, at 18.06, Phillip J. Eby wrote:At 05:32 PM 1/15/05 +0100, Just van Rossum wrote:Phillip J. Eby wrote:
> >It's not at all clear to me that "sticky" behavior is the best > >default behavior, even with implicit adoptation. Would anyone in > >their right mind expect the following to return [0, 1, 2, 3, 4, 5] > >instead of [0, 1, 2, 0, 1, 2]? > > > > >>> from itertools import * > > >>> seq = range(10) > > >>> list(chain(islice(seq, 3), islice(seq, 3))) > > [0, 1, 2, 0, 1, 2] > > >>> > > I don't understand why you think it would. What does islice have to > do with adaptation?
islice() takes an iterator, yet I give it a sequence.
No, it takes an *iterable*, both practically and according to its documentation:
But it _does_ perform an implicit adaptation, via PyObject_GetIter.
First, that's not implicit. Second, it's not adaptation, either. PyObject_GetIter invokes the '__iter__' method of its target -- a method that is part of the *iterable* interface. It has to have something that's *already* iterable; it can't "adapt" a non-iterable into an iterable.
Further, if calling a method of an interface that you already have in order to get another object that you don't is adaptation, then what *isn't* adaptation? Is it adaptation when you call 'next()' on an iterator? Are you then "adapting" the iterator to its next yielded value?
No? Why not? It's a special method of the "iterator" interface, just like __iter__ is a special method of the "iterable" interface.
So, I can't see how you can call one adaptation, but not the other. My conclusion: neither one is adaptation.
A list has no next()-method, but iter(list()) does.
But a list has an __iter__ method, so therefore it's an iterable. That's what defines an iterable: it has an __iter__ method. It would only be adaptation if lists *didn't* have an __iter__ method.
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