Perhaps @@unscopable shouldn't be a Set...
brendan at mozilla.org
Wed Apr 30 11:36:50 PDT 2014
Including Tom because proxies and MOP.
Erik Arvidsson wrote:
> This was never resolved and the spec is incomplete here
> On Wed Sep 25 2013 at 6:17:32 PM, Allen Wirfs-Brock
> <allen at wirfs-brock.com <mailto:allen at wirfs-brock.com>> wrote:
> So here is another concern, about the scheme we agreed to last week.
> It needs to match a found own property against the possibility of
> an own @@unscopable property on the same object and that object
> may be somewhere up the inheritance chain of the actual with
> object. The means that [[HasProperty]]/[[Get]]/[[Set]] can not be
> used to do those resolve binding in an ObjectEnvironmentRecord
> because they don't tell us where the property was found. Instead,
> ObjectEnvironmentRecord needs to reimplement its own property
> lookup using [[GetOwnProperty]] and [[GetInheritanceOf]].
> However, if the with object is a proxy that means we may be
> bypassing the actual inheritance mechanism implemented by the
> Proxy's 'has'/'get'/'set' traps and that could introduce
> observable semantics irregularities.
> Specifying the duplicated lookup is doable but a pain. That and
> the semantic issues WRT proxies makes me a lot less comfortable
> with the added complexity of supporting @@unscopable.
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