On Nov 9, 2011, at 4:00 PM, Brendan Eich wrote: > On Nov 9, 2011, at 3:48 PM, Axel Rauschmayer wrote: > >>>> Or are there other plans to get it solved? I would still love to see that >>>> happen, it’s a remarkably subtle source of errors. Could functions adopt >>>> the block-lambda semantics of picking up the `this` of the surrounding >>>> scope when not invoked as methods? It seems like that could work in strict >>>> mode where no one expects `this` to have a value. >>> >>> No, if you call such functions via object.method() references then this >>> binds to object. You can't break such compatibility only at runtime, and >>> only some of the time. >> >> Got it. I’m assuming that’s a performance issue? > > You could say that. If we inherit by default but it's a "soft binding", then > the inner function has to carry that reference with it, but in a way that can > be overridden. > > We talked about lexical this for functions long ago (Jan. 2008? at Google > anyway) and IIRC Mark found a subtler flaw.
But again, it's a runtime incompatible change, even ignoring performance. Code today may count on this == global in non-strict mode, or this === undefined in strict mode, for inner functions not called as methods. Making such a runtime-incompatible change uses up one of my "five fingers of fate" and it's not to be done lightly. /be _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
