On Nov 13, 2011, at 7:51 AM, Tom Van Cutsem wrote: > Hi Andreas, > > All good points, and I don't recall any of them being intentional. Your > points seem to suggest changing the semantics such that calling "new > fproxy()" on a function proxy without a construct trap should perhaps just > simply throw a TypeError.
I recall a bit of intention: we wanted to default to calling the call trap with a new object bound to |this|, as is done for user-defined functions. /be > > Now, in the direct proxies design, a missing [[Construct]] trap could simply > forward to the [[Construct]] internal method of the target (not the call > trap!). That would be cleaner (direct proxies no longer feature a "virtual" > prototype, they reuse the target's prototype anyway) and seems to be where we > were trying to take the current [[Construct]] trap default behavior. > Unfortunately, since current proxies don't have a target, we chose the call > trap, which isn't quite the right choice. > > Regarding the test case: I think it is broken (IMHO, it expects the most > intuitive result. Since the current semantics don't align with that > intuition, that's a good enough signal for me that we should probably change > the behavior to throw a TypeError). I'll update the test case. > > Cheers, > Tom > > 2011/11/10 Andreas Rossberg <rossb...@google.com> > I think the specification of [[Construct]] for function proxies may > not currently be doing what it is intended to do. If the proxy does > not have a construct trap, the method simply delegates to the > [[Construct]] method of the call trap. AFAICS, that has two > consequences: > > 1. The prototype is taken from the call trap, not from the proxy. > > 2. If the trap returns a primitive value, that will be ignored and > replaced with a freshly allocated object, as usual. > > It is not clear to me whether either was intended, but the former > seems surprising, and the latter is inconsistent with the behaviour > expected by the construct-primitive test case from > <http://hg.ecmascript.org/tests/harmony/>. > > Any ideas? > > /Andreas > _______________________________________________ > es-discuss mailing list > es-discuss@mozilla.org > https://mail.mozilla.org/listinfo/es-discuss > > _______________________________________________ > es-discuss mailing list > es-discuss@mozilla.org > https://mail.mozilla.org/listinfo/es-discuss
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