title: Reason for circular references with classes?
body: <p>I'm aware of circular references (Class A holds Class B and Class B holds Class A). But since I haven't programmed enough, it's hard for me to find reasons to use them. I was wondering if people could give me some examples and explain good reasons for using them.</p>
  
  <p>In my case, right now I'm looking at 2D source code tutorials and the user created a Creature and a CreatureAi class that reference each other. For what reason? I don't know yet, that's why I'm looking for examples and still reading around. </p>