On Tue, Mar 26, 2013 at 10:14 PM, David Bruant <[email protected]> wrote:
> Le 26/03/2013 22:56, Mark S. Miller a écrit : > > Because the weak-map-maker constructor grants no privilege and can be >> generally accessible, whereas the weak-ref-maker grants the privilege of >> being able to observe the non-determinism of GC, and so should not be made >> accessible to code that shouldn't have such powers. It is the same reason >> why Maps and Sets, which are enumerable, enumerate their elements in a >> deterministic order. >> >> In short, separation of concerns as well as separation of privileges. >> > If WeakMaps were granted the privilege of observing GC non-determinism via > iteration, I assume it would be through a default WeakMap.prototype.@@iterator > (that's how it works for Map). > Removing this authority can be done by providing another WeakMap > constructor with 'null' as WeakMap.prototype.@@iterator which is pretty > much as much work as removing access to the weak-ref-maker. > > Thanks to the iterator protocol (and especially the @@iterator symbol), > privileges can be kept separate, so I don't think it's a sufficient enough > reason to not allow iteration over WeakMaps if WeakRefs are in. WeakRefs are *not* in ES6, because getting these privilege separation issues right is hard, and is best done after real experience using the new module system. > > > David > > ______________________________**_________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/**listinfo/es-discuss<https://mail.mozilla.org/listinfo/es-discuss> > -- Text by me above is hereby placed in the public domain Cheers, --MarkM
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