Axel Rauschmayer schrieb:
wouldn’t the iteration protocol be simpler if iterators were always
closed (versus only if iteration finishes abruptly)?
Hm, I can't see much harm in that, it seemd to simplify the
implementation of iterators indeed. It changes the semantics from
| cleanup must be done before returning the iterresult
(that's how `finally` works) to
| after having returned the iterresult, you will be made to clean up
Or, actually, that doesn't sound as good. "Some will *hopefully* tell
you" to clean up is not what looks like good, resilient design.
While it does indeed simplify the producer implementation, the consumer
side does get more complicated - from
for (let iter=getIterator(), value, done; {value,done}=iter.next(),
!done; ) {
console.log(value);
// Assuming this never throws
}
to
let iter = getIterator();
for (let value, done; {value,done}=iter.next(), !done; ) {
console.log(value);
// Assuming this never throws
}
iter.return(); // additional line required
Of course, if done properly (accounting for exceptions) the change is
minimal - from try-catch to try-finally. But who does that, how often is
it forgotten?
Bergi
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