Proxy Classes

Sometimes, it is desirable to hide the implementation details of a class to prevent access to proprietary information (including private data) and proprietary program login in a class. Providing clients of your class with a proxy class that knows only the public interface to your class enables the clients to use your class's services without giving the client access to your class's implementation details.

• Proxy class
  • Hide implementation details of another class
  • Knows only public interface of class being hidden
  • Enables clients to use class's services without giving access to class's implementation
• Forward class declaration
  • Used when class definition only uses pointer to another class
  • Prevents need for including header file
  • Declares class before referencing
  • Format: class ClassToLoad;

Implementation of a proxy class is demonstrated in Figs. 2.29-2.31.

Figure 2.29: Implementation class definition.

Figure 2.30: Interface class definition.

Figure 2.31: Interface class member-function definitions and Implementing a proxy class.