Ember Mixins and the needs property - ember.js

Question

I have sort of a general question on how the controller needs property works with regard to mixins
Lets say I have a shopping card model that resides in the application controller so it's available everywhere in the app
// application route
export default Ember.Route.extend({
setupController: function(controller, model) {
this._super(controller, model);
controller.set('cart', this.store.createRecord('cart'));
}
});
Now any other controller that needs to use the cart, I want to provide a mixin:
// mixins/cart-access
export default Ember.Mixin.create({
needs: ['application'];
cart: Ember.computed.alias('controllers.application.cart')
});
// some controller
export default Ember.Controller.extend(CartAccess, {});
This is all well and good, but will it cause problems if in another controller I set the needs property to something else?
// some other controller
export default Ember.Controller.extend(CartAccess, {
needs: ['some-other-controller'] // not inlcuding application
});

Answer 1

Went ahead and did an experiment, and the needs from the mixin will be merged with the needs from the controller.
Example: https://github.com/DVG/need-experiment
//application route
export default Ember.Route.extend({
setupController: function(controller, model) {
this._super(controller, model);
controller.set('hello', "Hi!")
}
});
//hi mixin
export default Ember.Mixin.create({
needs: ['application'],
hello: Ember.computed.alias("controllers.application.hello")
});
//people contntroller
import Hi from 'needs/mixins/hi';
export default Ember.Controller.extend(Hi,{});
//posts controller
import Hi from 'needs/mixins/hi';
export default Ember.Controller.extend(Hi, {
needs: ['something-else']
});
//posts.hbs
{{hello}}
{{needs}}
The posts template displays "Hi!" and application,something-else