title: Angular interpolation expression not evaluated
body: <p>I am having an issue with Angular interpolation.</p>
  
  <p>I have a directive template that looks like this:</p>
  
  <pre><code>&lt;div class="autocomplete {{attrs.class}}" id="{{attrs.id}}"&gt;
       &lt;input type="text" {{attrs.autofocus | toAutofocusText}} ng-model="searchParam" placeholder="{{attrs.placeholder}}"/&gt;
       ...
  &lt;/div&gt;      
  </code></pre>
  
  <p>The problem I have is that this expression is not evaluated:</p>
  
  <pre><code>{{attrs.autofocus | toAutofocusText}}  
  </code></pre>
  
  <p>However, if I change this to something like this:</p>
  
  <pre><code>x="{{attrs.autofocus | toAutofocusText}}" 
  </code></pre>
  
  <p>It does get evaluated.</p>
  
  <p>Could someone explain me why this would be happening? I am guessing it is something fairly fundamental, but I can't find anything on Google. </p>