4. Two parts of the proper class design

• Properly designed classes have two parts:

  • the interface, which contains a set of public operations provided by the class

  • the implementation, which typically includes everything else:

    • data attributes

    • operations that are used by the object internally.

• Implementation is

  • what the user of an object does not see

  • what the user is not required to understand.

• For a designer of a class, it is crucial to understand who is going to be the audience of the class users.