title: How to do a PHP hook system?
body: <p>How do you impliment a hook system in a PHP application to change the code before or after it executes.  How would the basic architecture of a hookloader class be for a PHP CMS (or even a simple application).  How then could this be extended into a full plugins/modules loader?</p>
  
  <p>(Also, are there any books or tutorials on a CMS hook system?)</p>