title: Forward declaration & circular dependency
body: <p>I've got two classes, Entity and Level. Both need to access methods of one another. Therefore, using #include, the issue of circular dependencies arises. Therefore to avoid this, I attempted to forward declare Level in Entity.h:</p>
  
  <pre><code>class Level { };
  </code></pre>
  
  <p>However, as Entity needs access to methods in Level, it cannot access such methods, since it does not know they exist. Is there a way to resolve this without re-declaring the majority of Level in Entity?</p>