nested-dependent-keys

controllers.application.js

import Ember from 'ember';

const { Controller, get, set, computed } = Ember;

export default Controller.extend({
  appName: 'Ember Twiddle',
  lorem: {
    ipsum: { 
	    asd: 0,
  	  qwe: 0,
    }
  },
  
  sum: computed('lorem.ipsum.{asd,qwe}', function() {
    const asd = get(this, 'lorem.ipsum.asd');
    const qwe = get(this, 'lorem.ipsum.qwe');
    return asd + qwe;
  }),
  
  actions: {
    incrementAsd() {
      this.incrementProperty('lorem.ipsum.asd');
    },
    incrementQwe() {
      this.incrementProperty('lorem.ipsum.qwe');
    }
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
<button onclick={{action 'incrementAsd'}}>asd: {{lorem.ipsum.asd}}</button>
<button onclick={{action 'incrementQwe'}}>qwe: {{lorem.ipsum.qwe}}</button>
<br>
<br>
sum: {{sum}}
<br>
<br>

twiddle.json

{
  "version": "0.12.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.12.0",
    "ember-template-compiler": "2.12.0",
    "ember-testing": "2.12.0"
  },
  "addons": {
    "ember-data": "2.12.1"
  }
}