Question

I’ve been going through the Ember documentation and am seeing an inconsistency in where the _super method is being called when overriding init.

This is the most common and is what I’ve been using so far

var Foo = Em.Object.extend({
    init: function(){
        this._super();
        // ... my stuff ...
    }
});

last night I was reading through this write up and saw an example doing this

var Bar = Em.Object.extend({
    init: function(){
        // ... my stuff ...
        return this._super();
    }
});

It was actually an Ember.ContainerView in the code snippet.

Can anyone explain this? My code OCD is acting up and I can’t move on until I know.

Answer 1

In the documentation linked

 init: function() {
    var childViews = this.get('childViews');
    var descriptionView = App.DescriptionView.create();
    childViews.pushObject(descriptionView);
    this.addButton();
    return this._super();
  },

_super() is called AFTER the descriptionView is created and pushed onto the childViews array.

That’s because the superclass init implementation is going to take the childViews array and do stuff with it. If you called _super before adding the descriptionView to the array, it wouldn’t get processed by whatever init does….

I’m inferring, but that’s the way it works in Sproutcore, from which Ember derives, so I think it’s probably the same.