Bound functions as constructors

[ibolmo]

Bound functions as constructors

[arian]

This seems to pass the @jdalton test: http://jsfiddle.net/QF9ZA/2/

[cpojer]

Note that there are three different cases:

1.3 without native bind: fix this one
1.3 with native bind: √
1.2compat: ignore this

[arian]

This should fix 1.3 without compat or native bind: arian@5c1df58c0d0

[arian]

In new browsers this changes slows down bind significantly. In IE8 (about 10%) and 7 the difference is less, but still slower (of course) http://jsperf.com/function-proto-bind

[jdalton]

I think there is probably room to tweak a bit, but the speed diff doesn't concern me much. Doing things right could come at a cost and it makes sense now that native is faster than the updated fallback.

[ibolmo]

Agreed, and thanks to Arian's clarification 1.3 runs native if present and for 1.2 with compat runs a much slower version :(. Nevertheless, I guess the bench should compare against non native bind. Finally, agreed that there's only too much one can do to speed this up.

[cpojer]

I'm cool with this. We should only fix 1.3 (1.2compat is non-standard anyway) and only few browsers don't have bind natively, so we should be fine :) Pull Request !

[cpojer]

Oh man, Safari still doesn't have bind :o

[cpojer]

Also, we can probably use

(this && this != window)

as an adequate check.

@jdalton - what do you think?

[seanmonstar]

a check for this != window means it breaks in a headless environment.

[arian]

What about arian@b38e69f886

[jdalton]

@cpojer this could be none-window a lot of the time so that wouldn't do:

For example:

foo.bar = baz.bar.bind(baz, 'x', 'y');

Also ya'll could take it up a notch and implement a custom call/apply method too (I'll update my list to include that). By spec bound.call(thisArg, 'z') should ignore thisArg and curry args as if called like bound('z').

[arian]

@jdalton: that should already work: http://jsfiddle.net/arian/QF9ZA/6/

var other = function(){
    console.log(this.foo, arguments);
};
other.bind({foo: 'bar'})(); // → bar
other.bind({foo: 'bar'}, 'first').call({foo: 'yeah!'}, 'yooo'); // → bar, ['first', 'yeah!']

[jdalton]

@arian except if you call/apply with an instance of the bound function as the thisArg. It shouldn't be treated as new bound.

[arian]

So am I missing something? https://gist.github.com/1124879

[jdalton]

@arian add a test for .apply() too