Yes, there are still a couple of bugs related to this that I hope to get to before the ES6 spec is totally locked down.
Allen On Jan 14, 2015, at 11:40 AM, Domenic Denicola wrote: > If I recall this came up previously and Allen said it was a bug. (Everything > should use .return().) Hopefully he can confirm. > > -----Original Message----- > From: es-discuss [mailto:[email protected]] On Behalf Of Jason > Orendorff > Sent: Wednesday, January 14, 2015 14:37 > To: es-discuss > Subject: Automatic iterator.return() in contexts other than for and yield* > > In some cases a `for` loop will implicitly call `iterator.return()`: > > function gen() { > try { yield 0; } > finally { console.log("return was called"); } > } > > for (let x of gen()) > throw "fail"; // logs "return was called" > > This is to support iterators that want to clean up after themselves. > > Destructuring assignment doesn't call `.return()`: > > let obj = {set x(v) { throw "fail"; }} > [obj.x] = gen(); // return() is not called > > Neither do the Map/Set/WeakMap/WeakSet constructors: > > class MySet extends Set { > add(v) { throw "fail"; } > } > > let m = new MySet(gen()); // return() is not called > > Anyone remember the rationale for this? It seems like we should have just one > iteration protocol, and it should be "what `for` loops do", including > `iterator.finish()`. The collection constructors should be as mannerly as > `for`, right? > > Anyone remember the reasoning? Is it something to consider changing in ES7? > > -j > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
