Sorry, I meant remove the configurability check of the "getOwnPropertyDescriptor" and "getPropertyDescriptor" trap return values, and add a check as to whether the "defineProperty" trap return value is an object to fix the property to.
On Thu, Jun 16, 2011 at 8:12 AM, Sean Eagan <[email protected]> wrote: > How about *optional* property fixing as a compromise? We could > replace the configurability check of the "defineProperty" trap return > value with a check of whether the return value is an object, in which > case it would be treated as a property descriptor to fix the property > to, otherwise the return value would just be ignored. > > On Thu, Jun 16, 2011 at 4:18 AM, David Bruant <[email protected]> wrote: >> Le 16/06/2011 00:53, Mark S. Miller a écrit : >> >> On Wed, Jun 15, 2011 at 2:10 PM, David Bruant <[email protected]> wrote: >> >>> >>> In a way, the fixed properties proposal make proxies bicephal. For some >>> inputs (property names), they plug their handler-provided MOP-brain and >>> for some others, they plug a native object MOP-brain (ES5 - 8.12). These >>> brains cannot communicate. This is why changing .length in the "native >>> object brain" has no effect in the other brain (which handles numeric >>> properties(...unless some of these are non-configurable)). And I think >>> it has been said before, but there would be no logging possible for >>> non-configurable properties in the context of the fixed properties >>> strawman since native MOP-brain doesn't allow that. >> >> >> Cute metaphor. But as Tom's code showed, the proxy can create fixed >> (non-configurable) accessor properties whose getters and setters form a >> corpus callosum ;). >> >> Interactions with getter/setter is already a good thing, but I think it's >> not enough. ES5 offers a very fine-grained API to study objects. If we >> pretend to be able to emulate arrays based on proxies, we should be able to >> emulate everything including answering correctly when it comes to "is it a >> data or an accessor property descriptor?". >> For instance, for a data property descriptor, even if non-configurable, >> "writable" can be changed from true to false (then it cannot be changed >> afterward). This behavior is not possible when dealing with getter/setters. >> With fixed properties Tom's code, it is not possible to change an array's >> length from writable to not writable. Trying to do so would throw an error >> (because the property is non-configurable and any attempt to switch from >> accessor to data property descriptor throw an error (or just reject?)). >> >> I'd like to insist on the ability for proxies to be able to emulate native >> arrays (and new ES5 Object.* API interaction in particular) especially >> because currently, SpiderMonkey has a problem with redefining ".length" on >> arrays. See https://bugzilla.mozilla.org/show_bug.cgi?id=598996 >> I wish proxies to be able to compensate if there is such a bug (in any ES >> implementation) and I need this level of spec conformance. >> This discredits the current fixed properties proposal (especially the >> getter/setter compensation code), I think. >> >> David >> >> _______________________________________________ >> es-discuss mailing list >> [email protected] >> https://mail.mozilla.org/listinfo/es-discuss >> >> > > > > -- > Sean Eagan > -- Sean Eagan _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
