New Twiddle

controllers.application.js

import Ember from 'ember';
import { computed } from '@ember/object';

export default Ember.Controller.extend({
  init(){
    this._super(...arguments);
    var foo = {
       bar: "bar",
       baz: "baz"
    }
    this.value = "value";
    Ember.defineProperty(this, "test", computed(...Object.keys(foo), function(){
      // alert("I changed");
      return this.value;
    }))
  },
  appName: 'Ember Twiddle',
  actions: {
     updateBar(){
       this.set('value', 'bar');
       this.set('bar', 'BAR');
     },
     updateBaz(){
       this.set('value', 'baz');
       this.set('baz', 'BAZ');
     }
  }
  
});

templates.application.hbs

{{test}}
<br>
<p>This contrived example will only work once per button press</p>
<button {{action 'updateBar'}}> Update Bar</button>
<button {{action 'updateBaz'}}> Update Baz</button>

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}