Agreed. Just to clarify though, I'm going to make a pedantic change to your wording ;).
On Tue, Apr 23, 2013 at 6:00 AM, Andreas Rossberg <[email protected]>wrote: [...] > Preventing cross-realm prototype chains was not the intention. The > intention was to prevent using a protosetter from another realm to > mutate the [[Prototype]] of an object in a realm where Object.prototype.__proto__ > has been removed. > (In the case of a cross-realm prototype chain, the notion of "a prototype chain in a realm" is not well defined.) > > Here is my example again: > > // Realm A > delete Object.prototype.__proto__ // no messing around > > let other = getObjectFromSomewherePotentiallyAnotherRealmB() > > let p1 = Object.create(other, {a: {value: 1}}) > For example, at this point in your scenario, we would have no problem with other.__proto__ = {a: 2}; However, the is mutating at least one prototype *chain* that starts in Realm A. > let o = Object.create(p1) > let p2 = Object.create({}) > o.__proto__ = p2 // say what? > > Everything is fine up to the last step. In particular, o has a > cross-realm prototype chain just fine. The only problem is with the > last line, which actually makes use of the __proto__ inherited from a > different realm to mutate o's prototype. My understanding was that > _that_ is the kind of thing we anted to prevent. > > /Andreas > -- Cheers, --MarkM
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