Prequel and Principles
In many ways this book is a "prequel" to a book I wrote in 2002 entitled Agile Software Development: Principles, Patterns, and Practices (PPP). The PPP book concerns itself with the principles of object-oriented design, and many of the practices used by professional developers. If you have not read PPP, then you may find that it continues the story told by this book. If you have already read it, then you'll find many of the sentiments of that book echoed in this one at the level of code.
In this book you will find sporadic references to various principles of design. These include the Single Responsibility Principle (SRP), the Open Closed Principle (OCP), and the Dependency Inversion Principle (DIP) among others. These principles are described in depth in PPP.