Model Independence

• As mentioned earlier, the Model should be independent of the other classes
• In fact, the Model class shouldn't even "know" that the other classes exist
  
  
• This means:
  
  
  • The Model class should depend on variables that can be affected by the Controller class
  • That is, it should have some "setter" methods
    
    
  • If the Model class shouldn't even know that the View class exists, how can it ask to be redrawn when something changes?
  • The Model class should have a way of "telling the world" that something has changed