readonly bindings

components.my-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  isTouched: false,
  _isTouched: false,
  didUpdateAttrs(params) {
    if (params.oldAttrs.isTouched !== params.newAttrs.isTouched) {
      // isTouched did change. time to update internal property
      this.set('_isTouched', this.get('isTouched'));
    }
  },
  actions: {
    toggleIsTouched() {
      this.toggleProperty('_isTouched');
    },
    toggleSomeProp() {
      this.set('value', Math.random());
    }
  }
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  isTouched: true,
  actions: {
    toggleIsTouched() {
      this.set('isTouched', false);
    }
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{my-component isTouched=(readonly isTouched) value=value}}

<hr>

<button onclick={{action "toggleIsTouched"}}>
  Toggle controller's <code>isTouched</code>
</button>
<br>
{{#if isTouched}}
  controllers's <code>isTouched</code> is true!
{{else}}
  controllers's <code>isTouched</code> is false!
{{/if}}
<br>

<h3>Instructions</h3>
<ol>
  <li>Toggle the component's <code>isTouched</code></li>
  <li>Toggle the component's <code>value</code> to a random number.</li>
  <li>See that <code>isTouched</code> has changed.</li>
</ol>

templates.components.my-component.hbs

<button onclick={{action "toggleIsTouched"}}>
  Toggle component's <code>isTouched</code>
</button>
<button onclick={{action "toggleSomeProp"}}>
  Toggle some prop
</button>
<br>
{{#if _isTouched}}
  component's <code>isTouched</code> is true!
{{else}}
  component's <code>isTouched</code> is false!
{{/if}}

twiddle.json

{
  "version": "0.10.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.5.1",
    "ember-data": "2.6.1",
    "ember-template-compiler": "2.5.1"
  },
  "addons": {}
}