On Fri, Sep 13, 2013 at 11:36 AM, Tom Van Cutsem <[email protected]> wrote: > MarkM and I talked about conditional invocation offline and we convinced > ourselves to argue for the status-quo (i.e. continue to encode conditional > invocations as [[Get]]+[[Call]]). > > The most compelling argument we can think of is that [[Get]]+[[Call]] is > also the pattern JavaScript programmers use to express conditional method > calls today: > > var f = obj[name]; > if (f) { f.call(…); } else { … } > > No matter whether or how we extend the MOP, such code exists and will > continue to exist, and well-designed proxies that want to re-bind |this| > must already deal with this pattern by implementing the "get" trap > correctly.
Tom, it seems to me if there’s such a thing as “implementing the "get" trap correctly”, i.e. such that method calls work, that removes the main motivation for having [[Invoke]] in the first place. To recap what else [[Invoke]] achieves, in the light of that: * improved performance for proxies, because method calls go through one proxy handler trap rather than two, and no temporary function object is allocated * proxies can observe a bit about the caller (whether or not it's an [[Invoke]] call site), when a method is called If that's all, it seems like we should definitely remove [[Invoke]] and the .invoke trap. The MOP was already complicated enough. The performance argument is a non-starter, and the other “feature” is entirely undesirable. -j _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
