title: Is UML Class Diagram of Zend_Log correct?
body: <p><strong>Background of question</strong></p>
  
  <p>Analysis of Zend_Log reveals following Class Diagram</p>
  
  <p><strong>Zend_Log:</strong></p>
  
  <ul>
  <li>uses ReflectionClass &amp; Zend_Log_Exception</li>
  <li>maintains reference to array of Zend_Log_Writer_Abstract</li>
  <li>maintains references to array of Zend_Log_Filter_Interface</li>
  </ul>
  
  <p><strong>Zend_Log_Writer_Abstract</strong></p>
  
  <ul>
  <li>maintains reference to array of Zend_Log_Filter_Interface</li>
  <li>maintains reference to Zend_Log_Formatter_Interface</li>
  </ul>
  
  <p><img src="https://i.stack.imgur.com/hPy6D.jpg" alt="alt text"></p>
  
  <p><strong>Questions</strong></p>
  
  <ol>
  <li>Zend_Log_Filter_Interface relates with Zend_Log_Filter_Suppress, Zend_Log_Filter_Message &amp; Zend_Log_Filter_Priority as depicted, is this correctly laid out in Class Diagram?</li>
  <li>Is it okay to say that, the Zend_Log contains reference to array of Zend_Log_Filter_Interface and this is composition relationship (similarly for Zend_Log_Writer_Abstract)?</li>
  <li>As it is obvious that Zend_Log_Filter_Interface is contained by both Zend_Log &amp; Zend_Log_Writer_Abstract, while Zend_Log contains Zend_Log_Writer_Abstract, that makes Zend_Log_Filter referenced by both container (Zend_Log) and contained (Zend_Log_Writer_Abstract); is that some "Design Pattern", if yes what is the name?</li>
  </ol>
  
  <p>Regards!</p>