Re-entrant and Non Re-entrant Code

Re-entrant means that once a method is called on your object, it should be possible for someone else to call that method. For an example of something that’s non-re-entrant the IBM XML Parser (version 1.x) comes to mind. When certain methods are called on the IBM DOM parser, and exceptions are thrown the entire object becomes frozen and no one can call any more methods on that object. This is an example of non-reentrant code.