On Thu, Nov 17, 2011 at 12:04 PM, Allen Wirfs-Brock <[email protected]> wrote:
> OK, I have a fix for the missing constructor problem. See: > http://wiki.ecmascript.org/doku.php?id=strawman:class_operator#missing_constructors > > > The biggest thing I see missing is a declarative form that includes the name. I just think its so close, that to not include a form class Point {...} Which can desugar to create a var Point at the very least, would be a bit of a tragedy. I think most people will see the class operator and think about it as analogous to function. Another piece which might not be as big a deal is that [[ctor]] is not the same as 'constructor', and in the cases with a missing 'constructor', the result of 'class Proto' would seem like it makes (or fetches) a function that behaves like a proper constructor function, but it will result in an instance whose prototype does not have an own 'constructor' property. (I think I even confused myself with that, sorry) The alternative proposal I've been advocating that always creates a new function and prototype makes tradeoffs in the other direction. It does not require [[ctor]], or automatic .prototype references from constructor to the enclosing object literal. It also makes it trivial to include a name on the constructor function without mutation (because a new function is being made). OTOH, because it always creates a new function with a fresh prototype that points up to *UnaryExpression*, you get this important difference: let f = new Foo(); let isSame = (class f === Foo); //isSame is true for allen's proposal, but false for mine. //however, mine would behaviorally be the same (barring serious inspection) At this point, if Allen's proposal included a declaration form 'class Point {...}' I would be ready to get behind it. I still have a fondness for mine, which is used purely for defining classes, but for most cases, his would work equally well in the ways I would want to use it. - Russ
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