765: Highlights

• When you create lists, you should take care to restrict access to the header and link member variables by placing them in the private portion of the appropriate class definitions.
• Because the header class member functions require access to link member variables, and because the header class is not a natural subclass of the link class, you need to provide access by declaring the header class to be a friend of the link class.
• If you want one class to have access to the member variables and member functions in another, then declare that class to be a friend by instantiating the following pattern in the class with the member variables and member functions:

  friend class name of class to be granted access;