Le 24/09/2011 23:50, David Bruant a écrit : > Le 24/09/2011 22:25, François REMY a écrit : >> I really think Proxies provides all the functionnalities required to >> implement the special border cases where a non-conventionnal behavior >> is needed. > I do not think they do on their own, especially when it comes to object > identity (equality of objects after a call to Object.getPrototypeOf). > Proxies "suffer" from the same invariants than the regular objects which > is that Object.getPrototypeOf cannot lie (there is no trap for it). > > However, with proxies + redefining Object.getPrototypeOf + adding a > custom Object.changePrototype(object, newProto) (which would /virtually/ > change the prototype of a proxy (not a regular object!)), it could be done. Hi,
I just wanted to give a follow-up on that. I implemented it: https://github.com/DavidBruant/HarmonyProxyLab/tree/master/MutableProtoObjects ---- var o = MutableProtoObject({a:1, b:2}); console.log(o.a, o.b); // 1, 2 (inherited) o.b = 3; console.log(o.a, o.b); // 1 (inherited), 3 (own) Object.changePrototype(o, {a:2, b:4, c:1}); console.log(o.a, o.b, o.c); // 2, 3 (own), 1 delete o.b; console.log(o.a, o.b, o.c); // 2, 4, 1 // shadowing of b is over. ---- * MutableProtoObject is an equivalent to Object.create (without the second argument). * Object.changePrototype(o, newProto) works as you'd expect. * Only newly created objects with MutableProtoObject can have their prototype changed dynamically (while __proto__ can change built-ins) * There is no protection against prototype chain cycles (it wouldn't be hard to implement though). Also, I implemented another flavor of Forwarder (similar to [1]) which explicitly calls Object.getPrototypeOf when needed (which allows me to return a different value when needed). I have no opinion on whether it's better or worse, but i just wanted to point it out. David [1] http://wiki.ecmascript.org/doku.php?id=harmony:proxy_defaulthandler _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
