title: When should I use the Visitor Design Pattern?
body: <p>I keep seeing references to the visitor pattern in blogs but I've got to admit, I just don't get it.  I read the <a href="http://en.wikipedia.org/wiki/Visitor_pattern" rel="noreferrer">wikipedia article for the pattern</a> and I understand its mechanics but I'm still confused as to when I'd use it.</p>
  
  <p>As someone who just recently really <strong>got</strong> the decorator pattern and is now seeing uses for it absolutely everywhere I'd like to be able to really understand intuitively this seemingly handy pattern as well.</p>