An Introduction to Object-Oriented Programming

By Timothy Budd

Study Guide for Chapter 7

Learning Objectives

• Explain the concept of inheritance.

• Distinguish between a subtype and a subclass.

• Describe some of the ways in which inheritance is used.

• Describe both the costs and benefits of the use of inheritance.

Study Questions

1. Give a simple intuitive description of inheritance.

2. Explain how a subclass can be viewed as both an extension and a contraction of the parent class.

3. Explain the difference between a subclass and a subtype.

4. What is the principle of substitutability?

5. Explain why the principle of substitutability tends to be more important in statically typed languages than in dynamically typed languages.

6. Give an example of each of the following forms of inheritance.
   • Inheritance for Specialization
   • Inheritance for Specification
   • Inheritance for Construction
   • Inheritance for Generalization
   • Inheritance for Extension
   • Inheritance for Limitation
   • Inheritance for Variance
   • Inheritance for Combination

7. Which of the following forms of inheritance generate subtypes in addition to subclasses?
   • Inheritance for Specialization
   • Inheritance for Specification
   • Inheritance for Construction
   • Inheritance for Generalization
   • Inheritance for Extension
   • Inheritance for Limitation
   • Inheritance for Variance
   • Inheritance for Combination

8. Of the languages we are considering in this book, which require that all classes inherit from a common base class? What are some of the advantages of doing so?

9. Describe some of the benefits of using inheritance.

10. What is rapid prototyping?

11. Describe some of the costs of using inheritance.

12. Explain why raw execution speed should not be an overriding concern in software development.