Basic Subclassing

A class is transformed into a subclass by adding a "generalization" relationship from the subclass to the superclass (base class). On a class diagram this appears as a line between the two classes with an arrow pointing toward the superclass.

This means that the subclass inherits all the operations of the superclass, and in addition it may:

• Add extra functions;
• Modify the applicable options of the function in the superclass.

Consider two classes where MySubclass is a subclass of MyBaseClass:

• MyBaseClass has two operations: op1() and op2()
• MySubclass has three operations: op1(), op2() and op3() where op1 and op2 is inherited from MyBaseClass and MySubclass.op3 is provided only in the MySubclass class.