nkgm

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  array: ['a', 'b', 'c'],
  
  lengthBased: Ember.computed('array.length', function() {
    return this.get('array').join(" ");
  }),
  

nkgm

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  
  fullName: '',
  
  firstName: Ember.computed('fullName', function() {
		return this.get('fullName').split(' ')[0];
  }),

nkgm

import Ember from 'ember';

// A computed property chain of property(fullName) <- computed(firstName) <- computed(greeting) will 
// always recalculate computed(firstName) and computed(greeting) when property(fullName) changes. 
// This means that computed(greeting) will be recalculated even when computed(firstName) didn't change
// as a result of property(fullName)'s change. If you find yourself stuck in an "unnecessary expensive
// updates" situation, here is something you can do to optimize:
export default Ember.Controller.extend({
  appName: 'Optimizing computed property recalculation',