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[Python-ideas] Consider making enumerate a sequence if its argument is a sequence

Akira Li 4kir4.1i at gmail.com
Fri Oct 2 04:13:39 CEST 2015 
Steven D'Aprano <steve at pearwood.info> writes:
...
>> You've got the idea: the word *iterable* may be used in the context when
>> not all iterables are accepted.
>
> Sure. But the distinction is that while there are a whole lot of 
> different iterables:
>
> - iterables with a sufficiently small number of items
> - iterables of hashable items
> - iterables of (hashable key, item) pairs
> - iterables of prime numbers less than one million
> - iterables of strings containing exactly 1 vowel
>
> etc they are special cases and don't need specialised names. But there 
> is a *general* distinction between two cases:
>
> - iterables which are iterators
> - iterables which are not iterators
>
> We have a name for the first set: "iterators". But we don't have a name 
> for the second set. Andrew suggested "non-iterator iterables" is too 
> clumsy for general use, and suggests we need a better name. You 
> suggested "iterables", but that clearly cannot work, since iterators are 
> a kind of iterable.

I meant that you won't use the word *iterable* if your function accepts
_only_ iterators and therefore if I see *iterable" I expect that the
function can handle arbitrary iterables, not just iterators.

If your function rejects iterators then in practice it means that you
might want a re-iterable/re-runnable (that I see mentioned in the
thread) iterable (not an arbitrary "non-iterator iterable").

If there is no restriction that the same items should be produced the
second time ("rerunnable iterable"?)  then *collection" (introduced at
the top of the thread) may work. Though *collection* implies that an
iterable can't return the same (non-self) iterator -- otherwise an
iterator is also a collection.

I still don't see a practical need to avoid the word "iterable" unless
new requirements (in addition to being non-iterator) are present.
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