Clever (took me a moment to figure out what the comma operator does here...).
And makes sense: You would not want an invoker to have that kind of power.
If it wasn’t so negative for performance, I probably would apply curryThis() to
all of my methods:
var obj = {
method: function (self, arg) { // additional argument `self`
someFunction(..., function() {
self.otherMethod(arg);
});
}.curryThis(), // introduce an additional argument
otherMethod: function (arg) { ... }
}
Function.prototype.curryThis = function () {
var f = this;
return function () {
var a = Array.prototype.slice.call(arguments);
a.unshift(this);
return f.apply(null, a);
};
};
On Nov 10, 2011, at 1:15 , Mark S. Miller wrote:
> 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
--
Dr. Axel Rauschmayer
a...@rauschma.de
home: rauschma.de
twitter: twitter.com/rauschma
blog: 2ality.com
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