On Thu, Sep 12, 2013 at 12:38 AM, Jason Orendorff <[email protected] > wrote:
> On Wed, Sep 11, 2013 at 9:08 AM, Tom Van Cutsem <[email protected]> > wrote: > > Currently the pattern for this is [[Get]]+[[Call]]. We cannot refactor to > > [[Has]] + [[Invoke]] in general, because [[Has]] will return true also > for > > non-callable values. > > > > If we believe these are call-sites where it is worth avoiding the > allocation > > of a function, then having an additional internal method like > [[GetMethod]] > > or [[InvokeConditional]] makes sense, but I doubt it's worth the added > > complexity. > > But as Allen said, [[Invoke]] is not a performance hack. It's a > correctness hack. > > It permits proxies to customize their behavior around `this`, and even > naive .invoke trap users would definitely want those customizations to > apply for implicit .toString() and .then(). > I agree, anything else would be surprising. But can't we make the .invoke trap work for both [[Invoke]] and [[InvokeConditional]]? It would just always be called, and the places where [[InvokeConditional]] is used in the spec would treat it as though the required method exists on the receiver.
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