title: ngClass - creating a class name containing angular expression
body: <p>I would like to create class names based on an the evaluation of an angular expression, but it seems that angular is removing these expressions from the eventually compiled classes. When iterating over cells, assume the following code:</p>
  
  <pre><code>&lt;td ng-class="{'label{{cell.count}}': !!cell.count}"&gt;&lt;/td&gt;
  </code></pre>
  
  <p>My goal is that when cell.count = 1 the resulting class will be "label1", when cell.count = 2, "label2", etc.
  In practice, what happens is that angular discards the expression in the eventual class - As long as !!cell.count, I get the class "label" regardless of the count. How can I achieve this?</p>