On Wed, Nov 9, 2011 at 4:00 PM, Brendan Eich <bren...@mozilla.com> wrote:
> On Nov 9, 2011, at 3:48 PM, Axel Rauschmayer wrote:
>
> We talked about lexical this for functions long ago (Jan. 2008? at Google
> anyway) and IIRC Mark found a subtler flaw.
>
I think my original example was smaller and more elegant. But the following
is adequate to demonstrate the problem:
function Outer(secret) {
"use strict";
this.v = secret;
this.w = secret * 2;
this.x = secret * 3;
this.InnerPoint = function(x, y) {
this.x = x;
this.y = y;
};
this.InnerPoint.prototype = {
getX: function() { return this.x; },
getY: function() { return this.y; }
};
}
Alice does:
var outer = new Outer(mySecret);
var innerPoint = new outer.InnerPoint(3,5);
bob(innerPoint); // passed innerPoint to Bob, who Alice does not trust.
Today, Bob, receiving innerPoint, has no way to obtain Alice's secret.
Given your proposal, Bob could do
(1,innerPoint.getX)() / 3;
Today, if Bob does that, the getX call fails when it tries to evaluate
undefined.x.
--
Cheers,
--MarkM
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