title: C++ Expat and XML parsing
body: <p>I am new to using expat. I am trying to figure out how XML_SetUserData is intended to do. In my case, I have a list of class A objects and I need to populate this list as I parse the XML stream.</p>
  
  <p>So far, I was planning on using a singleton to represent this single list. 
  Is the XML_SetUserData to eliminate the need for my list being a singleton?</p>