Chapter 1: Preliminaries—Os(OO) andDesign Patterns 101Normally a book of this sort would start with a quote from Christopher Alexander, thearchitect (of buildings) who came up with the notion of a design pattern. I've found thatthough Alexander is a brilliant man who writes wonderful books, his prose can be a bitopaque at times, so I'll skip the mandatory quote. His ideas launched the entire designpatternmovement, however.Similarly, the seminal book on design patterns in software is Gamma, Helm, Johnson,and Vlissides's Design Patterns: Elements of Reusable Object-Oriented Software(Addison-Wesley, 1995). (The four authors are jokingly called the Gang of Four by mostworking designers.) My book wouldn't exist if the Gang-of-Four book hadn't been written,and I (and OO programmers in general) owe an enormous debt of gratitude to the authors.Nonetheless, the Gang-of-Four book is a formal academic presentation of patterns, andmost beginners find it too dense to penetrate. At the risk ...