Catch-all proposal based on proxies

Mike Samuel mikesamuel at
Mon Dec 7 16:44:35 PST 2009

Under "This avoids questions like:",
does the proposal also avoid
   5. Can property trapping be defined on host objects

"The Type of a Proxy"
Why does the type change upon fixing?
Is it an error to pass a value v s.t. (typeof v !== 'function') to
Proxy.createFunction?   Specifically RegExps?

Would defining a Proxy.proxies(proxy, obj) that returns true iff obj
was the argument to Proxy.create{,Function} that created proxy allow a
useful level of equality checking?  That would allow limited checking
by code that already possesses a handle to the underlying object
without potentially leaking an underlying object to a bad proxy.

"[[DefaultValue]] (hint)"
The rule for "[[Class]]" means that it's possible to create proxy an
array in every way but that the isArray test used by common libraries
cannot be spoofed:
     '[object Array]' !==
What is the proper behavior here?

2009/12/7 Tom Van Cutsem <tomvc at>:
> Dear all,
> Over the past few weeks, MarkM and myself have been working on a proposal
> for catch-alls for ES-Harmony based on proxies. I just uploaded a strawman
> proposal to the wiki:
> Any feedback is more than welcome. Note that the proposal is quite lengthy,
> which is mostly due to the fact that it also includes a detailed semantic
> specification of proxies (in ES5-spec-style) in addition to just its API
> description. If you're not interested in the specification details, you can
> skip the section named "Semantics".
> Cheers,
> Tom
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