[Harmony proxies] Non-configurable properties: fixed properties VS trap all with invariants enforcement

David Bruant david.bruant at labri.fr
Sun Jul 3 13:55:16 PDT 2011


Le 03/07/2011 22:49, Mark S. Miller a écrit :
> [+stay]
>
> I'd rather have a bug filed whose resolution we can postpone deciding.
> I'll file it later today.
Ok. cc me (bruant at enseirb.fr), please.

> The reason this is more important than it may appear is that there are
> at least two other proxy implementations in progress that are probably
> using FF as a reference, perhaps modulo the filed FF proxy bugs as
> well as the speced semantics.
oooooh... Are these implementations available somewhere?

David

>
>
> On Sun, Jul 3, 2011 at 12:44 PM, David Bruant <david.bruant at labri.fr
> <mailto:david.bruant at labri.fr>> wrote:
>
>     Le 03/07/2011 21:32, Mark S. Miller a écrit :
>>
>>
>>     On Sun, Jul 3, 2011 at 11:07 AM, David Bruant
>>     <david.bruant at labri.fr <mailto:david.bruant at labri.fr>> wrote:
>>
>>         Le 03/07/2011 14:59, Tom Van Cutsem a écrit :
>>         > As a follow-up to the fixed properties proposal:
>>         >
>>         > I created a prototype implementation of fixed properties on
>>         top of the
>>         > existing Proxy API. The idea is to wrap an existing proxy
>>         handler in a
>>         > FixedHandler. This FixedHandler does the bookkeeping and
>>         checking to
>>         > ensure that the wrapped handler doesn't misreport
>>         non-configurable
>>         > properties.
>>         >
>>         > Full source code available here:
>>         >
>>         <http://code.google.com/p/es-lab/source/browse/trunk/src/proxies/FixedHandler.js>
>>         Just to make sure I do not misunderstand your work:
>>         - Your code relies on current Proxy implementation behavior
>>         (FF4&5)
>>         which doesn't do any check on the "configurable" attribute for
>>         defineProperty and get{Own}PropertyDecsriptor traps
>>
>>
>>     I didn't know that. Is there a bug filed on this yet or a test
>>     case that demonstrates this bug?
>     -----
>     var h = {getOwnPropertyDescriptor:function(name){return {value:1,
>     configurable:false};}};
>     var p = Proxy.create(h);
>
>     console.log( Object.getOwnPropertyDescriptor(p, 'a') );
>     -----
>     I just tried on Firebug (FF5) and it returned
>     {"value":1,"writable":false,"enumerable":false,"configurable":false}.
>     Should have returned configurable:true according to current proposal.
>     There is no bug filed I would be aware of. But I think there is no
>     rush and it can wait until decisions are made at the July TC39
>     meeting, no? If the some form of the fixed property proposal is
>     accepted, it would replace any bug filed asking to always return
>     true for configurability.
>     Proxies bugs haven't received much attention lately anyway as far
>     as I know.
>
>     David
>
>
>
>
> -- 
>     Cheers,
>     --MarkM

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