2013/9/11 Brendan Eich <[email protected]> > 3) For proxy trap invocations I maintain we are still better off with >> [[Get]] + [[Call]] to keep double-lifting as simple as possible. >> > > Sorry if I missed it: what complicates things if we use [[Invoke]] to > support double-lifting?
Trap method calls on the handler are conditional: if the handler doesn't implement a trap, the proxy will forward to the target instead. Currently we call handler.[[Get]] + verify whether the result is callable. In the case of double-lifting, this means the meta-handler only has to implement the "get" trap. If we would have a hypothetical [[ConditionalInvoke]] with corresponding trap, then the meta-handler would just implement that trap instead. This would work. Any other solution that uses 2 methods (e.g. [[Has]]+[[Invoke]], [[Get]]+[[Invoke]], [[Get]]+[[InvokeFunction]]) will require the meta-handler to implement 2 traps. Again, this is not fatal, but it does make the pattern uglier. Cheers, Tom
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