Refactoring (Part 2)

• Introduce Foreign Method
  Create a method in the client class with an instance of the server class as its first argument.
• Introduce Local Extension
  Create a new class that contains these extra methods. Make this extension class a subclass or a wrapper of the original.
  
  Organizing Data:
  
• Replace Data Value with Object
  Turn the data item into an object - during initial stages of development, your data is simple. As development proceeds you realize that those simple items aren't so simple anymore - turn it into an object.
• Duplicate Observed Data
  You have domain data available  only in a GUI control, and domain methods need access - Copy the data to a domain object. Set up an observer to synchronize the two pieces of data.
• Change unidirectional Association to Bidirectional
  You have two classes that need to use each other's features, but there is only a one-way link - Add back pointers, and change modifiers to update both sets.
• Replace Magic Number with Symbolic Constant