title: Extending a class with common functionality
body: <p>I have three classes which basically do very similar things;</p>
  
  <ol>
  <li>Store a record of an uploaded file.</li>
  <li>Move and upload the file.</li>
  <li>Set the status of the record to active or revoked.</li>
  </ol>
  
  <p>One of the classes has an additional update method. Each class references a different table in the database because although some of the fields are common, there are a couple of fields extra in some of the tables.</p>
  
  <p>As quite a lot of the functionality is common I think it may be best to extend a base class rather than duplicating a lot of the functionality.</p>
  
  <p>My only quarrel is the construct function on the base class. As some of the fields in each table are additional I'm concerned this will prevent a base class.</p>
  
  <p>I have thought of using an abstract class as this will allow me to extend on functionality whilst maintaining most of the things in one place. But it's the problem with the construct. Can I have an abstract class with no construct?</p>
  
  <p>Any ideas?</p>