Principles of Package Design

Apply design principles to your classes, preparing them for reuse. You will use package design principles to create packages that are just right in terms of cohesion and coupling, and are user- and maintainer-friendly at the same time.

The first part of this book walks you through the five SOLID principles that will help you improve the design of your classes. The second part introduces you to the best practices of package design, and covers both package cohesion principles and package coupling principles. Cohesion principles show you which classes should be put together in a package, when to split packages, and if a combination of classes may be considered a “package” in the first place. Package coupling principles help you choose the right dependencies and prevent wrong directions in the dependency graph of your packages.

What You’ll Learn

• Apply the SOLID principles of class design
• Determine if classes belong in the same package
• Know whether it is safe for packages to depend on each other

Who This Book Is For

Software developers with a broad range of experience in the field, who are looking for ways to reuse,share, and distribute their code

Part I: Class Design

Chapter 1: The Single Responsibility Principle

Chapter 2: The Open/Closed Principle

Chapter 3: The Liskov Substitution Principle

Chapter 4: The Interface Segregation Principle

Chapter 5: The Dependency Inversion Principle

Part II: Package Design

Chapter 6: The Release/Reuse Equivalence Principle

Chapter 7: The Common Reuse Principle

Chapter 8: The Common Closure Principle

Chapter 9: The Acyclic Dependencies Principle

Chapter 10: The Stable Dependencies Principle

Chapter 11: The Stable Abstract ions Principle

Chapter 12: Conclusion

About the Author

Matthias Noback is a professional PHP developer. He runs his own web development, training, and consultancy company called Noback’s Office. In the past, he has worked as a software developer at Driebit (Amsterdam) and IPPZ (Utrecht), and as CTO at Ibuildings (Utrecht). Since 2011 he has been regularly writing on his blog about advanced software development topics. Favorite topics include software architecture, legacy code, testing, and object design