[[Extensible]]and Proxies (Was: Proxy.isProxy )

Brendan Eich brendan at mozilla.com
Fri Jul 15 12:47:59 PDT 2011

On Jul 15, 2011, at 12:38 PM, Allen Wirfs-Brock wrote:

> On Jul 15, 2011, at 11:16 AM, Allen Wirfs-Brock wrote:
>> But can't a Proxy based object do all sorts of nasty back channel stuff even while it maintains the apparent object freeze invariants?
> Duh, of course a frozen object really isn't a Proxy any more as currently defined. But is has also lost all useful intercession  derived semantics.

This may be ok, so long as we can distinguish preventExtensions from seal from freeze, *and* determine the class or constructor used for the newborn object that becomes the proxy. Yes, I'm thinking faithful Array emulation.

> BTW, if http://wiki.ecmascript.org/doku.php?id=strawman:fixed_properties was extended to support Object.preventExtensions we might not have anything to argue about except perhaps performance issues. 

Indeed, that helps quite a bit. Glad to hear it.

But there may be more power needed in the fix trap, per the above Array-proxy test.

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