It looks like [[OwnPropertyKeys]] is defined to return an iterator. But the ordinary [[OwnPropertyKeys]] method produces the List of keys to be iterated eagerly, and pretty every place that calls the method immediately consumes the entire iterator. So there is no actual laziness.
This is weird. I think it would be clearer for [[OwnPropertyKeys]] to return a List of PropertyKeys. Except for proxies, this doesn't change behavior. Here are the changes needed to implement this: * In 9.1.12, the ordinary object [[OwnPropertyKeys]] method, change step 3 to just say "Return keys." instead of "Return CreateListIterator(keys)." * In 9.5.12, the Proxy [[OwnPropertyKeys]] method, treat the return value as an iterable (not an iterator) and convert it to a List of PropertyKeys using IteratorStep, IteratorValue, and ToPropertyKey. Change the NOTE to describe the new invariant. * In 19.1.2.1 Object.assign, 19.1.2.8.1 GetOwnPropertyKeys, 19.1.2.14 Object.keys, and 19.1.2.15.1 MixinProperties, drop the IteratorStep boilerplate. * In 26.1.10 Reflect.ownKeys(), convert the result of calling [[OwnPropertyKeys]] to an Array using CreateArrayFromList. Note that 7.3.10 SetIntegrityLevel and 7.3.11 TestIntegrityLevel already assume that [[OwnPropertyKeys]] returns a List, as proposed. -j _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
