+1!
It would be great if someone will explain in detail why
Object.setPrototypeOf is no go.
We definitely need mutable prototype, but having it via __proto__ really
breaks the language.
Any function that blindly extends object with provided hash is affected e.g.
extend(obj, { __proto__: Error.prototype }).
Additionally it means that we need to serialize any user input which
eventually may be used as key on a dictionary e.g. data[userDefinedName].
That's bad, and it's hard for me to believe we can't do it better.
François REMY-3 wrote:
>
> I certainly agree, but it has been decided otherwhise by the TC39 members
> and I doubt they’re willing to revert their decision.
>
>
>
>
>
>
> De : Andrea Giammarchi
> Envoyé : 18 mars 2013 17:08
> À : Nathan Wall
> Cc : [email protected]
> Objet : Re: Mutable Proto
>
>
>
> I would like to see Object.setPrototypeOf(object, proto) too and a
> disappeared __proto__ 'till now breaking too much.
>
>
>
> It would be much easier to implement all shenanigans via
> Object.defineProperty(Object.prototype, '__proto__', {whatever}); rather
> than fix current non-standard __proto__ ...
>
>
>
>
> +1
>
>
>
>
> On Mon, Mar 18, 2013 at 9:04 AM, Nathan Wall <[email protected]> wrote:
>
> A previous thread [1] brought to my attention the fact that objects which
> don't inherit from Object.prototype won't have mutable __proto__. This
> was something I had missed and breaks some scripts I'm currently using
> because I have objects which I don't want to inherit from Object.prototype
> but for which I do want to have mutable proto.
>
> Testing in Firefox Nightly I found this workaround:
>
> var x = { }, y = { foo: 'bar' };
>
> x.__proto__ = y;
> console.log(1, x.foo);
> // => 1 'bar'
>
> x.__proto__ = null;
> console.log(2, x.foo);
> // => 2 undefined
>
> x.__proto__ = y;
> console.log(3, x.foo);
> // => 3 undefined
>
> var _setPrototype = Object.getOwnPropertyDescriptor(Object.prototype,
> '__proto__').set,
> setPrototypeOf = Function.prototype.call.bind(_setPrototype);
> setPrototypeOf(x, y);
> console.log(4, x.foo);
> // => 4 'bar'
>
> Is this workaround a temporary bug in Firefox's current implementation? Or
> will this be the spec'ed behavior for ES6? Can we use such a method to
> mutate prototype on objects which don't inherit from Object.prototype?
>
>
> [1] https://mail.mozilla.org/pipermail/es-discuss/2013-March/029176.html
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>
-----
Mariusz Nowak
https://github.com/medikoo
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