Le 12/12/2012 21:09, Kevin Reid a écrit :
On Wed, Dec 12, 2012 at 12:03 PM, David Bruant <[email protected]
<mailto:[email protected]>> wrote:
Le 12/12/2012 20:49, Kevin Reid a écrit :
I haven't made it public yet, but it's just the obvious
implementation of an (old-style, as implemented in
Firefox/Chrome) proxy with a switchable “target”.
Interesting. As I said, target-switching won't be possible in
direct proxies.
I understand that direct proxies have an internal “target” object.
Will it not be possible to simply never place any properties on said
object (thus not constrain future behavior) while still appearing to
have properties? This text suggests that is a possible and expected
pattern:
Since this Proxy API requires one to pass an existing object as a
|target| to wrap, it may seem that this API precludes the creation
of fully “virtual” objects that are not represented by an existing
JSObject. It’s easy to create such “virtual” proxies: just pass a
fresh empty object as the target to |Proxy| and implement all the
handler traps so that none of them defaults to forwarding, or
otherwise touches the|target|.
In my case there is an actual object, of course, but I implement
forwarding to said object myself; the JS implementation never knows
that I am “treating it as a target”.
I was a bit too strong in my statement, sorry. Let me rephrase: the
internal [[Target]] can't be changed, but a proxy can emulate changing
of "fake" target as long as what happens with this "fake" target doesn't
involve invariant checking.
That's the reason I was suggesting that WindowProxies could (maybe
depending on how the object reference was obtained) throw whenever
invariant checks are involved.
David
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