unknownPrivateSymbol trap (was: WeakMap better than Private Symbols? (was: direct_proxies "problem"))

Herby Vojčík herby at mailbox.sk
Tue Jan 15 13:14:57 PST 2013

Tom Van Cutsem wrote:
> 2013/1/15 David Bruant <bruant.d at gmail.com <mailto:bruant.d at gmail.com>>
>     Le 15/01/2013 20:32, Tom Van Cutsem a écrit :
>>     As far as I recall, the purpose of the trap was to allow a
>>     membrane or revocable proxy to explicitly abort accesses involving
>>     such private symbols. The point being that if a membrane can't
>>     abort such accesses, then collaborators on both sides of the
>>     membrane could circumvent the membrane by communicating via a
>>     previously agreed upon private symbol.
>     Yes, we've discussed that in length with Nathan Wall :-)
> Sorry, I only now catched up with that. I don't have anything more to
> add to that discussion.
> So in conclusion:
> - we still need unknownPrivateSymbol

Is it needed? Maybe the "fail/forward" decision canbe set beforehand, 
when creating the proxy. Then, no trap will be called (but you cannot 
change the response in time; OTOH, is there a use case for it?).

Or does it do something more sophisticated then just telling "forward" 
or "fail" for situation that I am accessing some unknown private symbol?

> - a return/throw protocol may be more suitable than a boolean return
> value for this "trap"
> Cheers,
> Tom


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