The SuperBell company uses a Person object from which it inherits general information such as name and ID. From this, both Customers and Employees (CSR and OE Clerk) are inherited.

			attributes ID firstName lastName initial methods giveName add remove
		Person
	Customer		Employee
attributes ID firstName lastName initial *salutation methods giveName add remove					attributes ID firstName lastName initial *SSN methods giveName add remove
		OE Clerk		CS Rep.

Inheritance Definition

Inheritance is often represented as a tree. Moving down the tree, classes become more specialized, more honed toward an application. Moving up the tree, classes are more general; the contain members suitable for many classes but are often not complete.

Specialization

Generalization

Figure 2-3 Specialized and Generalization

Objects rarely fall into completely distinct groups;there is often considerable overlap in the operations of object groups.

Changing Inherited Members

You might not always want a specialized subclass to inherit all the members of the superclass, or to inherit the members exactly as they are. To customize the members for a subclass, you can override superclass members. Overriding keeps the member but chenges the implementation.

You might need to override a method if the superclass provides a default implementation that is not optimal. Specific subclasses may override it to provide optimal implementations in light of the specific context in which they are used. For example,better algorithms or caching and storage techniques may be possible in specific derived classes.

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