[Harmony Proxies] Proposal: Property fixing

Brendan Eich brendan at mozilla.com
Wed Jun 15 16:01:42 PDT 2011


On Jun 15, 2011, at 3:53 PM, Mark S. Miller wrote:

> On Wed, Jun 15, 2011 at 2:10 PM, David Bruant <david.bruant at labri.fr> wrote:
> Le 15/06/2011 23:01, Tom Van Cutsem a écrit :
> > Just realized: even though an arrayProxy could update its fixed
> > "length" property, it would not be able to intercept updates "from the
> > outside" (i.e. updates to "length" by objects other than the handler).
> > I guess that capability is also needed to be able to "shrink" an array
> > if its "length" is decreased.
> 
> There's something I don't understand about this whole conversation. Why does our emulated array need to claim that its length property is a non-configurable data property, as opposed to
> * a non-configurable accessor property
> * a configurable data property
> * a configurable accessor property
> ?
> There can't be any ES3 code that would be broken by any of these other choices, since ES3 code can't ask about these attributes.

ES5 code can. Isn't that enough of an objection? People are filing bugs over such observable (with ES5's meta-object API) differences among engines, especially in the DOM where this is driving the WebIDL spec.

/be

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