title: Macro before class name
body: <p>I was recently looking over some code and I've stumble upon this:</p>
  
  <pre><code>class IDATA_EXPORT IData {
      /* .... */
  }
  </code></pre>
  
  <p>Where <code>IDATA_EXPORT</code> is not more than :</p>
  
  <pre><code>#ifndef IDATA_EXPORT
      #define IDATA_EXPORT
  #endif
  </code></pre>
  
  <p>What is <code>IDATA_EXPORT</code> in this case? (I mean, is it type like int, char etc ... ?)</p>