title: how does $parse work in a directive?
body: <p>I've managed to play with directive attribute listener without using isolated scope (<code>$watch</code>, <code>$observe</code> and <code>$parse</code> - a pleasure) but I experience difficulties understanding the last one. </p>
  
  <p>Here's my html : </p>
  
  <pre><code>&lt;div active="setActiveNav(number1)"&gt;&lt;/div&gt;
  </code></pre>
  
  <p>And my directive :</p>
  
  <pre><code>link: function(scope,elem,attr){
      scope.myFunction = $parse(attr.active);
      ...
  }
  </code></pre>
  
  <p>But can you explain how do I fire the function passed in my 'active' attribute ?</p>