On Wed, Apr 30, 2014 at 4:06 PM, Allen Wirfs-Brock
<[email protected]> wrote:
>
> On May 1, 2014, at 2:50 AM, Jason Orendorff <[email protected]> wrote:
>
>>
>> As specified, proxies can do this:
>>
>> js> Object.isFrozen(proxy)
>> true
>> js> Object.getOwnPropertyDescriptor(proxy).configurable
>> true
>
> No, that is not the intent.
André got it right. Here is the proxy I had in mind:
var proxy = new Proxy(Object.freeze({prop: undefined}), {
ownKeys: function () {
return ["prop"];
},
getOwnPropertyDescriptor: function name() {
let n = 0;
return {get configurable() { return n++ > 0; }, enumerable: true};
}
});
Currently in SpiderMonkey:
js> Object.isFrozen(proxy)
true
js> Object.getOwnPropertyDescriptor(proxy, "prop").configurable
false // but only because we don't implement [[Origin]]
> Also note that Object.isFrozen is specified to operates at the level of the
> MOP operations and property descriptor records, not at the
> Object.getOwnPropertyDescriptor/descriptor object level. It never looks at
> the object that is passed through [[Origin]].
Agreed.
> It isn’t clear exactly what you intend by the above snippet (does proxy have
> a ‘getOwnPropertyDescriptorHandler’? did you really mean to use undefined as
> the property key?).
Oh. No to the latter. Sorry for the typo!
> In either case, if the object passes the criteria for isFrozen then then the
> con configurable attribute of the resulting descriptor (if the property
> exists) must be false and consistent with the target.
The only inconsistency here is that Object.getOwnPropertyDescriptor is
returning an [[Origin]] object which is then tricking the end user.
-j
_______________________________________________
es-discuss mailing list
[email protected]
https://mail.mozilla.org/listinfo/es-discuss
