New Twiddle

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  
  value: false,
  
  latch: Ember.computed('value', '_latch', function() {
    if(this.get('_latch')) { return this.get('_latch') }
    if(this.get('value')) { this.set('_latch', this.get('value')) } 
    return this.get('value');
  })
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>

value: {{value}}
latch: {{latch}}
_latch: {{_latch}}
<button {{action (mut value) true}}>Set Value True</button>
<button {{action (mut value) false}}>Set Value False</button>

twiddle.json

{
  "version": "0.13.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.16.2",
    "ember-template-compiler": "2.16.2",
    "ember-testing": "2.16.2"
  },
  "addons": {
    "ember-data": "2.16.3"
  }
}