title: Problems with circular includes in PHP 5.3
body: <p>We're testing out a migration to php 5.3, and are seeing some odd issues.  Trying to track down exactly what happens.  Here's a simplified scenario.</p>
  
  <p>File a.php</p>
  
  <pre><code>include_once(b.php);
  class A {....
  </code></pre>
  
  <p>File b.php</p>
  
  <pre><code>include_once(a.php);
  class B extends A {....
  </code></pre>
  
  <p>In reality, the circular references happen through a much more convoluted path, with various other includes.  But, the main idea is, when it gets to the definition of class B, it throws a Fatal error, because it didn't have a definition for class A.</p>
  
  <p>Thoughts?  We're trying to clean up our includes to hopefully prevent these circular references, but I'm curious as to why this fails, particularly seeing that it may be version-dependent.</p>
  
  <p>Thanks!</p>