title: Input helper ember reverse disabled state
body: <p>I want to disable an inputfield if a property is false or does not exist. To do this, you should need a reverse binding for the input helper, something like (pseudo code):</p>
  
  <pre><code>{{ input ... disabled=!isNew}}
  </code></pre>
  
  <p>After reading the <a href="http://emberjs.com/guides/templates/input-helpers/" rel="nofollow">docs</a>, I could find nothing about reverse boolean structure. </p>
  
  <p>Should I solve this by using a computed property*, or is there a better way?</p>
  
  <hr>
  
  <p>*
  Something like:</p>
  
  <pre><code>loginFieldDisabled: function() {
      return ! this.get('isNew');
  }.property('isNew')
  </code></pre>