add some easy way to bind Signal.dispatch()

[millermedeiros]

one thing that I always have to do is to make sure Signal.dispatch() is called on the right context, specially when it needs to be called on a callback, eg:

$('#foo').fadeOut(500, ended.dispatch); // won't work!

The case above doesn't work because this inside dispose() points to the wrong object (jQuery calls the callback passing the element as this). A solution is to create another function that is bound to the proper context:

// works
$('#bar').fadeOut(500, dispatchEnded);

function dispatchEnded(){
  ended.dispatch();
}

The main reason why I didn't auto bind the dispatch() context is because I was unsure if it would make it harder to subclass another signal, but we can simply reuse the method of the prototype like this:

function Signal(){
  var self = this;
  this.dispatch = function(){
    Signal.prototype.dispatch.apply(self, arguments);
  };
  // ...
}

If the user can instantiate a Signal he can also access the Signal.prototype which is enough to grab the unbound method and reuse it (like CompoundSignal does).

Overall I think it will avoid more problems than it will cause, specially since most people don't understand how scope works in JS and the advanced users will know a way around it (call the prototype method directly).

[millermedeiros]

Another solution is to add a new method to the dispatch() function that does the binding:

function Signal(){
  var self = this;
  this.dispatch.bind = function(){
    return function(){
      self.dispatch.apply(self, arguments);
    };
  };
  // ...
}

Which would be used like this:

$('#foo').fadeOut( 500, ended.dispatch.bind() );

I like the automagical approach better - calling bind() without any argument fells weird and user might not know he needs to do that.

[shovemedia]

If you're using signals, you really ought to understand scope. That said, I'm down.

[millermedeiros]

this shipped on v0.9.0

[wookieb]

"since most people don't understand how scope works in JS" I understand your point but that's their problem. Additionally the change is not consistent - why not autobind other methods like halt, forget? They can also be used as callbacks.

IMHO autobinding for dispatch should be removed.