On 24 January 2012 20:24, Brendan Eich <[email protected]> wrote:
> I am skeptical we will banish var, ever. Consider the object detection
> pattern:
>
> if (!this.foo) {
> var foo = function () {
> ...
> };
> }
>
> No way to make this work with let.
Actually, it is possible if this is a check for a primordial, and you
move them to the prototype of global this and allow shadowing them.
Then you'd be able to write:
let foo = Object.getPrototypeOf(this).foo || function() { ... }
(I think we had something like this on the board once.) Or, in the
browser, if window was actually bound to that prototype, this
simplifies to:
let foo = window.foo || function() { ... }
I don't think compatibility can afford binding window to something
different than global this, though. (One could still pre-bind the
prototype to a different name, however.)
Of course, I sincerely hope that the module system will provide a more
pleasant replacement for this pattern. :)
/Andreas
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