On Feb 13, 2012, at 11:43 AM, Gavin Barraclough wrote: > On Feb 13, 2012, at 9:55 AM, Allen Wirfs-Brock wrote: > >> Finally, an alternative to extending [[Get]] and [[Put]] would be to extend >> the GetValue abstraction operation (8.7.1) and the Simple Assignment >> evaluation semantics (11.13.1). >> >> [[DefineOwnProperty]] and [[Delete]] still need to be extended but, >> independent of any of the above, these two can probably be made over-riding >> implementations on Object.prototype rather than extending the default >> implementations used by all objects. > > > Hi Allen, > > I don't know if this is helpful, but Mark's strawman seemed to make this much > simpler, perhaps it might make for a less intrusive specification to define > that this should behave as if it is an accessor property following Mark's > ProtoGetter/ProtoSetter descriptions, whilst leaving how the property is > reflected ambiguous? I think this should amount to the same thing, just > might be easier to encapsulate this way?
I believe what that amounts to is specifying the property as (not "as if") an accessor property with ProtoGetter/ProtoSetter get/set functions and then specifying a [[GetOwnProperty]] over-ride for Object.prototype.__proto__ that allows an implementation to choose between returning a data property descriptor and returning a accessor property descriptor with censored get/set functions. There would still need to be a way to specify that special treatment of __proto__ in object literals is disabled when Object.prototype.__proto__ is modified or deleted. While this could be done with prose I think using [[Delete]] and [[DefineOwnProperty]] hooks (and the UnderscoreProtoEnabled variable) is a more precise why to specify what actions are required to actually disables __proto__. In general, I prefer preciseness over conciseness in the specification. Also, I think we need some more thought about how the approaches (specified as accessor vs. specified as [[Put]]/[[Get]] extensions) differ in the presence of proxies. Allen
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