Overview

This chapter introduces the concept of design patterns.

In this chapter,

• I discuss the origins of design patterns in architecture and how they apply in the discipline of software design.

• I discuss the motivations for studying design patterns.

Design patterns are part of the cutting edge of object-oriented technology. Object-oriented analysis tools, books, and seminars are incorporating design patterns. Study groups on design patterns abound. It is often suggested that people learn design patterns only after they have mastered basic object-oriented skills. I have found that the opposite is true: learning design patterns early in the learning of object-oriented skills greatly helps to improve understanding of object-oriented analysis and design.

Throughout the rest of the book, I will discuss not only design patterns, but also how they reveal and reinforce good object-oriented principles. I hope to improve both your understanding of these principles and illustrate why the design patterns being discussed here represent good designs.

Some of this material may seem abstract or philosophical. But give it a chance! This chapter lays the foundation for your understanding of design patterns. Understanding this material will enhance your ability to understand and work with new patterns.

I have taken many of my ideas from Christopher Alexander's The Timeless Way of Building.^[1] I will discuss these ideas throughout this book.

^[1] Alexander, C., Ishikawa, S., Silverstein, M., The Timeless Way of Building, New York: Oxford University Press, 1979.