On 9/10/14, 4:11 PM, Allen Wirfs-Brock wrote:
In practice (because of for-of semantics) Iterators need to be Iterables that return themselves as the associated iterator. All built-in iterators in ES have this characteristic
Ah, I see. But that's observably different from just doing the loop manually, since someone can change things like %ArrayIteratorPrototype% [@@iterator], right?
For example, Array.from does that kind of argument discrimination: http://people.mozilla.org/~jorendorff/es6-draft.html#sec-array.from
Yes, I'm aware. I was looking at that earlier today while writing up <https://github.com/heycam/webidl/pull/18>.
It slightly differs from what the outcome of the Web IDL discussion was in that it commits to an iterator if CheckIterable returns anything other than undefined, whereas the outcome of the thread I linked earlier was that we want to commit if CheckIterable returns a callable... It _would_ make some sense to align the two; at this point I can't recall why it was we decided to do the callable check in the IDL version, nor do I know why the ES spec decided to not do a callable check in this situation.
Other than that, I basically copied what Array.from/TypedArrayFrom does, yes. Including the not calling IteratorClose bit. ;)
-Boris _______________________________________________ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
