2012/11/13 David Bruant <[email protected]> > For the particular case you've written, when going for > hasOwnProperty.call or the in operator, the JS engine knows it needs to > output a boolean, so it can "rewrite" (or contextually compile) your trap > last line as "e===undefined" (since "undefined" is falsy and objects > created by object literals are truthy). In that particular case, the > allocation isn't necessary provided some simple static analysis. > Maybe type inference can be of some help to prevent this allocation in > more dynamic/complicated cases too. I would really love to have > implementors POV here. >
I'm very skeptical of this. If I may summarize, you're arguing that we can get away with spurious allocations in handler traps because JS implementations can in theory optimize (e.g. partially evaluate trap method bodies). I think that's wishful thinking. Not that implementors can't do this, I just think the cost/benefit ratio is way too high. Cheers, Tom
_______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
