Method binding
Ruby has method objects (Method and UnboundMethod) for passing references
to an object’s methods, so you can call a method without having a reference to
the object. JavaScript has functions and treats them as first-class values, so
you can get a reference to a method and call it later:
var rex = new Dog('Rex');
var spk = rex.speak; // a reference, we are not calling the method
spk('biscuits');
// -> "MY NAME IS AND I LIKE BISCUITS!"
Where did Rex’s name go? The thing is, we’ve not called spk through the
object rex, so this inside the function no longer refers to the right
thing. jsclass gives each object a method() method, that returns a method
by name, bound to its source object. This method is simply a JavaScript
function that you can call on its own and maintain the binding of this:
var speak = rex.method('speak');
speak('biscuits');
// -> "MY NAME IS REX AND I LIKE BISCUITS!"
You can also do this with class methods, since classes are objects too:
var User = new JS.Class({
extend: {
create: function(name) {
return new this(name);
}
},
initialize: function(name) {
this.username = name;
}
});
var u = User.method('create');
u('James') // -> {username: 'James'}