On Apr 11, 2011, at 9:21 PM, David Bruant wrote: > Actually I was wrong I think. With the introduction of proxies, ES > engines won't be able to trivially prevent pd allocation as they could > with regular objects just based on static analysis (since static > analysis will often fail at saying whether the function will be used > with regular objects or proxies as first argument)
Static analysis is conservative, yes. But type inference often can say what exact types |this| and other arguments have. Anyway, this isn't about absolute guarantees unless JS provides an API to query without allocating :-P. > I think it could be possible if we had a native Object.hasOwnProperty > method since that's really what we need here (that's what a static > analysis optimization would do internally). That was left out on purposes during ES3.1/ES5 design to keep things minimal. And of course Proxies built on that API. So probably we should leave this as an optimization challenge (GC, type inference, both if possible). /be _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
