On Sep 29, 2014, at 1:41 PM, Jason Orendorff wrote: > On Mon, Sep 29, 2014 at 3:02 PM, Allen Wirfs-Brock > <[email protected]> wrote: >> I can't imagine what you would want be to try to say about non-EMCAScript >> functions. Their internal "call" semantics is determined by the semantics of >> their implementation language. > > Function.prototype.apply, Function.prototype.call, and Reflect.apply > currently call PrepareForTailCall. Is this a bug?
No, I don't believe so. Built-ins (whether implemented in ES or native) are specified to have an "execution context". The PrepareForTailCall release that execution context for before performing a [[Call]]. It's working in the above functions just like it works from any other call site. In other words, the spec. language says that these buil;t-ins functions explicitly end with an ECMAScript tail call. > > I can see that the current language in 14.6.3 PrepareForTailCall only > covers "tail position calls" and "resources associated with the > currently executing function execution context", but what's wrong with > copying that sentence into 19.2.3.3 and changing it to refer to "the > internal method call in the last step of the above algorithm" and > "resources associated with the current call to > Function.prototype.call"? > > The spec constrains the behavior of builtins in all kinds of ways, > regardless of what language they're written in. I don't understand > what is special about stack space usage that makes it off-limits. I'm not sure what would be the point of duplicating the language. Since those functions use PrepareForTailCall, what is says applies to them. Allen _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
