title: Passing in element properties to ng-class expressions
body: <p>I was wondering if it's possible to use <code>ng-class</code> and supply an expression that's based on the inner content of the element it's being used on.</p>
  
  <p>So for example, say I have:</p>
  
  <pre><code>&lt;table&gt;
      &lt;tr ng-repeat="result in results"&gt;
          &lt;td ng-class="vm.getNumberClass(...)"&gt;
              {{vm.getSomeMagicNumber(result)}}
          &lt;/td&gt;
      &lt;/tr&gt;
  &lt;/table&gt;
  </code></pre>
  
  <p>Could I pass in the value of the <code>td</code> cell content as an argument to the <code>getNumberClass</code> function I am using as an expression on the <code>ng-class</code> directive?</p>
  
  <p><strong>EDIT</strong></p>
  
  <p>When I say pass in the value of the td cell content, I mean pass in the evaluated result of <code>{{vm.getSomeMagicNumber(result)}}</code> as an argument</p>
  
  <p>I could do something like.</p>
  
  <pre><code>&lt;td ng-class="vm.getNumberClass(vm.getSomeMagicNumber(result))"&gt;
      {{vm.getSomeMagicNumber(result)}}
  &lt;/td&gt;
  </code></pre>
  
  <p>Whilst this does work for my scenario, it feels like a performance hit as its calling the function twice</p>