I coded up a hypothetical Proxy.createConstructor function that creates a function proxy initialized according to ES5.1 section 13.2: < https://gist.github.com/1183514>
Given the ease with which this can be expressed, I'm not sure it merits dedicated support, unless I overlooked something. Cheers, Tom 2011/8/31 Tom Van Cutsem <[email protected]> > 2011/8/30 Brendan Eich <[email protected]> > >> On Aug 30, 2011, at 2:16 PM, David Bruant wrote: >> >> Actually that's what current function proxies do by default (no .prototype >> unless otherwise specified). My suggestion is to put a .prototype by default >> with keeping the option to opt-out (same with .length, etc.) >> >> Right, of course function proxies have to trap in order to emulate >> .prototype and other properties. >> > > Indeed, that was our intent: fproxy.prototype and fproxy.length are > determined by the handler via the "get" trap. > This should work fine for fproxy.prototype (and it is actually consulted > when evaluating |obj instanceof fproxy|.) > > For fproxy.length, the handler object can only return the call trap's > length if it has a reference to the call trap, which as David points out, in > the general case it does not. OTOH, typically a function proxy will wrap > some other target function f, in which case the handler would simply return > f.length, so I don't know whether this issue is such a big deal. > > If one wraps an existing function f using the default ForwardingHandler > like so: > var fproxy = Proxy.createFunction(new ForwardingHandler(f), f); > > Then fproxy.prototype, .length, .arguments, and .caller will all work as > expected. So the default ForwardingHandler is in a sense already the > convenient library that Andreas alluded to. > > I do notice that .prototype and .length are non-configurable properties, so > that ups the ante for proxies being able to emulate non-configurable > properties (more about that later). > > Cheers, > Tom >
_______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
