On Thu, Feb 9, 2012 at 4:11 PM, Allen Wirfs-Brock <al...@wirfs-brock.com> wrote:
> I've written a draft __proto__ specification for the working draft of the > ES6 spec. > > Just the __proto__ part of the spec. can be seen here: > http://wiki.ecmascript.org/lib/exe/fetch.php?id=strawman%3Amagic_proto_property&cache=cache&media=harmony:draft_proto_spec_.pdf<http://wiki.ecmascript.org/lib/exe/fetch.php?id=strawman:magic_proto_property&cache=cache&media=harmony:draft_proto_spec_.pdf> > > > Hi Allen, regarding B3.1.1 and B3.1.2, I was afraid it would have an effect on the spec like that. This is a hack which crufts up the working of some of the most basic operations of the language. For those who would try to prove properties about programs in the language, this extra complexity is where they can least afford it. But given the behavior you're trying to specify, I don't see how to do better than this. As I wrote earlier in response to Herby: On Mon, Jan 30, 2012 at 7:13 AM, Mark S. Miller <erig...@google.com> wrote: > -1 to adding yet another attribute to the object model (expanding it 16%) > unless the payoff is huge. Your UnderscoreProtoEnabled wouldn't seem to be as bad as that, since it is an internal property rather than an attribute. But it is an internal property effecting the behavior of the default [[Get]], [[Put]], and [[DefineOwnProperty]], whose semantics are already way more complex than we'd like. If we can't indeed specify this behavior in a less invasive way than this, then I would rather see us adopt the approach advocated by Gavin and written up in the current strawman: The dynamic semantics is fully explained by a non-magical accessor property, that appears to be an accessor property, and whose setter is a genuine first class function with the exclusive ability to mutate the [[Prototype]] internal property of extensional objects in its frame. This approach is much much cleaner. It is more permissive, as Brendan points out, but not in a way that needs to harm security. Regarding B3.1.3, in step 3 of the first algorithm, where does P come from? -- Cheers, --MarkM
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