Allen Wirfs-Brock wrote:
On Jul 15, 2013, at 10:30 PM, Brendan Eich wrote:
Axel Rauschmayer wrote:
The (x === Object(x)) test evaluates to true for value objects in this proposal, though. This may break code looking for
"primitives" but we need to see what such code expects. Is it filtering out the legacy typeof-result primitives (plus
"null"), trying to find values for which typeof currently returns "object" or "function"? If so, I
don't see a problem: int64, bignum, etc. are not legacy primitives. Is this test looking for objects that are their own wrappers?
Again all is well, unless "mutable wrapper" is assumed -- but that's not safe in the ES5 era to assume, anyway.
The most frequent use case I’ve encountered: does the value have a prototype
(i.e., will Object.getPrototypeOf() work)?
I’m assuming that value objects will have a prototype, accessible via
Object.getPrototypeOf (?)
Yes, they are after all value objects :-P.
js> Object.getPrototypeOf(0UL)
0UL
In the latest spec. draft, Object.getPrototypeOf(new Symbol) returns null
because that is what the [[GetInheritance]] MOP operation produces for exotic
symbol objects. That's because symbols symbols aren't supposed to have any
observable properties.
[[GetInhertance]] would do something else for value objects that actually
exposed inherited properties.
As it should:
js> Object.getPrototypeOf(0UL) === uint64.prototype
true
for toString and valueOf at least.
/be
_______________________________________________
es-discuss mailing list
es-discuss@mozilla.org
https://mail.mozilla.org/listinfo/es-discuss
