Sorry, I'd dropped too much context. Out of context, it looked like an argument that could be applied both to instance variables and to lexical variables. As applied only to instance variables, I'll hold off until I have a coherent opinion ;)
On Fri, Mar 16, 2012 at 4:22 PM, Brendan Eich <[email protected]> wrote: > Mark S. Miller wrote: > >> I agree with Waldemar. Classes aside, since code like >> >> { >> //...foo... >> let x = 3; >> function foo() { return x; } >> //... >> } >> >> is statically legal, and is only wrong if foo is called before x is >> initialized, the dynamic dead zone is very valuable. Otherwise, the call to >> foo() silently proceeds with a meaningless result. >> >> If you'd really rather have silent meaninglessness, use "var" instead of >> "let". >> > > Classes are sugar for objects with properties, though -- rememeber, we > agreed to sugar the protoypal pattern, not the closure pattern. > > A declared variable binding is different from an object property. They > aren't the same thing. > > And properties can be used before initialization in JS today (and in Dart > -- you Google guys are not all following the same rules :-P). > > It seems to me you're not agreeing or disagreeing with anything about > classes as prototypal sugar, rather you're trying to reason about > properties by pointing to let binding rules. Last July I flagged classes as > subject to conflict and confusion in TC39 due to this declaration vs. > property conflation. If we can't agree to avoid it by letting properties by > properties, then classes are indeed "out" for ES6 -- and out of Harmony for > now. > > /be > >> >> >> On Fri, Mar 16, 2012 at 3:50 PM, Brendan Eich <[email protected]<mailto: >> [email protected]>> wrote: >> >> Brendan Eich wrote: >> >> We can defer these by deferring guards and const instance >> properties, and tried to do so. But IIRC at least Waldemar was >> not happy leaving writable instance properties usable (with >> default value undefined) before being initialized. >> >> >> Of course, Dart allows this and discloses null on use before >> initialization: >> >> class Foo { >> var a; >> Foo(a) { >> print(this.a); >> this.a = a; >> } >> } >> main() { >> var foo = new Foo(42); >> print('main: ' + foo.a); >> } >> >> Tested at http://dartlang.org/. >> >> >> /be >> ______________________________**_________________ >> es-discuss mailing list >> [email protected] <mailto:[email protected]**> >> >> >> https://mail.mozilla.org/**listinfo/es-discuss<https://mail.mozilla.org/listinfo/es-discuss> >> >> >> >> >> -- >> Cheers, >> --MarkM >> ______________________________**_________________ >> es-discuss mailing list >> [email protected] >> https://mail.mozilla.org/**listinfo/es-discuss<https://mail.mozilla.org/listinfo/es-discuss> >> > -- Cheers, --MarkM
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