[Harmony Proxies] Proposal: Property fixing

Mark S. Miller erights at google.com
Thu Jun 16 11:26:15 PDT 2011

On Thu, Jun 16, 2011 at 10:13 AM, David Bruant <david.bruant at labri.fr>wrote:

> Le 16/06/2011 18:15, Mark S. Miller a écrit :
> > I do not believe so. The host object contract for configurable shows
> > that the only meaning it ever had in ES5 that one could count on is
> > "this is not guaranteed not to be magical". The proxy spec already
> > allows the same violations of the first two meanings you suggest:
> > * a proxy and a compliant ES5 host object may refuse to delete a
> > configurable property, and
> > * a proxy and a compliant ES5 host object may refuse an attempt to
> > reconfigure a configurable property.
> >
> > In summary, "configurable" was never a guarantee of anything.
> > "non-configurable" was the only state that came with guarantees. Let's
> > not weaken those.
> Ok, with this defintion, it makes sense to not let proxies lie on
> property configurability.
> So does it even make sense to want non-configurable (fixed) properties
> on proxies?
> Back to Sean's initial e-mail on this thread, why would we want
> individual non-configurable properties on proxies?
> As a side note, if all properties are described as configurable, then, a
> forwarding proxy will not properly forward when it comes to returning a
> property descriptor if the target has a non-configurable property.

As far are I can tell, the only reason anyone is asking for non-configurable
properties on trapping proxies is the issue raised by your side note. But
for this issue, I see no need to allow fixing of individual properties on
trapping proxies.

> David

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