prototype bind support?

[espruino-discuss]

Posted at 2014-11-19 by d0773d

Hi, my question kind of relates to my question from: generic pause/wait? I'm trying to wrap my head around how prototypeing works. does the Espruino support bind? For example:

setTimeout(function (e) { this.getSensorReading(); }.bind(this), w); //Attempting to execute getSensorReading()

I receive error:

Uncaught Error: Function "bind" not found!
 at line 8 col 58
...this.getSensorReading(); }.bind(this), w); //Attempting to e...
                               ^
in function "getSensorResult" called from line 1 col 20
ph.getSensorResult();

[gfwilliams]

Posted at 2014-11-19 by @gfwilliams

Hi - I'm afraid it doesn't support it yet... It's on my list though :)

So the issue you have is that 'this' generally gets reset when you call setTimeout - however you can still access any other local variables. The easiest way around it (the one that I tend to use in examples/modules) is:

var sensor = this;
setTimeout(function (e) { sensor.getSensorReading(); }, w);

[espruino-discuss]

Posted at 2014-11-19 by d0773d

Works like a charm :)

[espruino-discuss]

Posted at 2015-03-31 by @allObjects

@d0773d, @gordon just most recently made .bind() work / implemented... see this conversation. Now you do not need the application defined anonymous function anymore, and the .bind() is more efficient in all ways.

[espruino-discuss]

Posted at 2015-04-06 by d0773d

@allObjects thanks for updating my post. I will definitely impliment bind().

[espruino-discuss]

Posted at 2015-04-20 by WebReflection

As temporary work around on top of your file:

Function.bind||(Function.prototype.bind=function(c){var f=this,a=[].slice.call(arguments,1);return function(){a.push.apply(a,arguments);return f.apply(c,a)}});

In case you don't care about handling extra arguments ...

Function.bind||(Function.prototype.bind=function(c,f){f=this;return function(){return f.apply(c,arguments)}});

Until it's solved, of course

[gfwilliams]

Posted at 2015-04-20 by @gfwilliams

Function.bind actually exists and works fine now, so hopefully you shouldn't need to do that...

[espruino-discuss]

Posted at 2015-04-20 by WebReflection

Actually I've just realized Function.bind is there indeed but Function.prototype.bind is not ... but (function(){}).bind is there too ... oh well, good to know (sort of weird)

[gfwilliams]

Posted at 2015-04-20 by @gfwilliams

Yes, that's not right... Something strange is going on there - Thanks for letting me know.

It still works though - I think it's just the way it appears.