2012/10/8 David Bruant <[email protected]> > If the internal [[Enumerate]] only deals with own properties, it seems > that the enumerate trap can be removed and for..in loop can use the keys > and getPrototypeOf traps instead (as it does with regular objects which was > my point 2).
It all sounds plausible. For proxies and for-in loops there's an important inversion-of-control though: currently the proxy takes control of a for-in loop (it decides whether to continue the loop with its prototype), with your proposal the proxy would lose that control. For all other traps that may be called during a prototype-chain-walk (get, set, has) the proxy always gets to "virtualize its prototype chain". Even if not adopting the changes I just suggested, it seems that we need > some harmonization between the proxy traps and the internal [[Enumerate]] > signatures. > Indeed. If we stick with the current [[Enumerate]](includePrototype, onlyEnumerable) signature we'll need an ugly preamble for proxies: - when includePrototype is false and onlyEnumerable is true, call the keys trap - when includePrototype is false and onlyEnumerable is false, call the getOwnPropertyNames trap - when includePrototype is true and onlyEnumerable is true, call the enumerate trap - any other combination should not occur Cheers, Tom
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