Conceptually it is a set but I don't think anyone cares enough to oppose this being an array given that it is a cleaner layering of the spec.
On Wed, Sep 25, 2013 at 1:07 PM, Allen Wirfs-Brock <[email protected]> wrote: > At last weeks TC39 meeting we had consensus that the value of the > @@unscopable property should be a Set > https://github.com/rwaldron/tc39-notes/blob/master/es6/2013-09/sept-17.md#53-unscopeable > > As I begin to look at implementing this (and the other @@unscopable changes > from the meeting) I'm not so sure that Set is such a good idea. My basic > concern is that @@unscopable operates at a very low level of the ES name > binding resolution mechanism. Set exists at a much higher conceptual level > of the ES library and (until now) there was nothing in the fundamental > language semantics of ES that depends upon the existence of a library Set > object. Now that I have thought about this, it seems fundamentally wrong to > unnecessarily create such an up-dependency. > > I think we will have a cleaner semantics if we continue to treat an > @@unscopable value as an array-like object for the purpose of accessing its > property blacklist. Implementations, if they wish, can us2 caching scheme to > obtain sub-linear time access to an @@unscopable blacklist. > > In light of this consideration, does anybody still want to argue that we > should require an @@unscopable value to be a Set instance? > > Allen > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > -- erik _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
