Wonderful. +1. Thanks! On Thu, Jun 18, 2009 at 9:15 AM, Allen Wirfs-Brock < allen.wirfs-br...@microsoft.com> wrote:
> >-----Original Message----- > >From: Brendan Eich [mailto:bren...@mozilla.com] > > > >> BTW, I haven't yet perceived that we have consensus on putting this > >> into ES5. My interpretation of Brendan's initial comments on the > >> matter was that he was opposed to it for ES5. (I'm sure he'll let > >> us know whether or not that is correct). > > > >It's late in the game, but a sentence about [[Prototype]] seems > >doable. I defer to you on this, since you're Editor and it'll fall > >upon you to draft the change. > > > > OK, I'll put it in. Here is what I am inserting into section 8.6.2 > following the paragraph about [[Prototype]] that comes immediately after > table 4: > > Every ECMAScript object has a Boolean-valued [[Extensible]] internal > property that controls whether or not named properties may be added to the > object. If the value of the [[Extensible]] internal property is false then > additional named properties may not be added to the object. In addition, if > [[Extensible]] is false the value of the [[Prototype]] internal property of > the object may not be modified. Once the value of an [[Extensible]] > internal property has been set to false if may not be subsequently changed > to true. > > NOTE > This specification defines no ECMAScript language operators or built-in > functions that permit a program to modify an object's [[Prototype]] internal > property or to change the value of [[Extensible]] from false to true. > Implementation specific extensions that modify [[Prototype]] or > [[Extensible]] must not violate the invariants defined in the preceding > paragraph. > > > > Notice that I also made sure that [[Extensible]] cannot go from false to > true which was also previously unstated in the specification. > Allen > -- Cheers, --MarkM
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