On Oct 13, 2011, at 5:15 AM, David Bruant wrote:
> Le 13/10/2011 02:03, Allen Wirfs-Brock a écrit :
> ...
> So far so good
>
>> console.log(s instanceof Array); //true
> i think that this should be false.
> Object.getPrototypeOf(s) is the value of Object.getPrototypeOf(this) in the
> constructor which is the anonymous function 'prototype' property (fresh
> object inheriting from Object.prototype with the methods you added).
> My understanding of <| is that it sets the [[prototype]] property and nothing
> else. Consequently, I think that the semantics of "Array <| function(...){}"
> is to create a function with the prototype chain as follow:
> (anon function) --> Array --> Function.prototype --> Object.prototype -->
> null
> And unless otherwise specified, (anon function).prototype is a fresh object
> inheriting from Object.prototype (not Array.prototype)
that was the original idea but a couple of months ago the <| spec was updated:
"If the LHS operand has a property named prototype and the RHS operand is a
function expression then the [[Prototype]] of the function object is set to the
LHS object and the prototype property of the new function is set to a new
object whose [[Prototype]] is the value of the LHS’s prototype property."
(http://wiki.ecmascript.org/doku.php?id=harmony:proto_operator )
>
> But I think that the following should work:
> -----
> var SubArray = function(...values) {
> return Object.getPrototypeOf(this) <| [...values];
> }
> SubArray.prototype = Array.prototype <| {/*additional "subclass" methods*/};
you'd also need to include a constructor property in the new object in order to
make s instanceof SubArray work properly. The <| spec was revised as above in
order to ensure this all works automatically.
Allen
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