Often, software engineers and architects work with large, complex code bases that they need to scale and maintain. With this cookbook, author Maximiliano Contieri takes you beyond the concept of clean code by showing you how to identify improvement opportunities and their impact on production code. When it comes to reliability and system evolution, these techniques provide benefits that pay off over time.

Using real life examples in JavaScript, PHP, Java, Python, and many other programming languages, this cookbook provides proven recipes to help you scale and maintain large systems. Every section covers fundamental concepts including readability, coupling, testability, and extensibility, as well as code smells—symptoms of a problem that requires special attention—and the recipes to address them.

As you proceed through this book, refactoring recipes and the variety of code smells increase in complexity. You will:

• Understand the benefits of clean code and learn how to detect code smells
• Learn refactoring techniques step by step
• Gain illustrative code examples in several modern programming languages
• Get a comprehensive catalog of common code smells, their impacts, and possible solutions
• Use code that's straight to the point, favoring readability and learning

Table of Contents

Chapter 1. Clean Code

Chapter 2. Setting Up the Axioms

Chapter 3. Anemic Models

Chapter 4. Primitive Obsession

Chapter 5. Mutability

Chapter 6. Declarative Code

Chapter 7. Naming

Chapter 8. Comments

Chapter 9. Standards

Chapter 10. Complexity

Chapter 11. Bloaters

Chapter 12. YAGNI

Chapter 13. Fail Fast

Chapter 14. Ifs

Chapter 15. Null

Chapter 16. Premature Optimization

Chapter 17. Coupling

Chapter 18. Globals

Chapter 19. Hierarchies

Chapter 20. Testing

Chapter 21. Technical Debt

Chapter 22. Exceptions

Chapter 23. Metaprogramming

Chapter 24. Types

Chapter 25. Security

From the Preface

Code is everywhere, from web development to smart contracts, embedded systems, blockchains, James Webb’s onboard software system, surgical robots, and many other domains. Software is effectively taking over the world, and we are currently witnessing the rise of professional artificial intelligence code-generation tools. That means clean code is more important than ever. As you continue to work in increasingly large proprietary or open source codebases, clean code is the way of keeping it fresh and ready to evolve.

Who This Book Is For

This book helps you identify common problems in a codebase and highlights the consequences of these problems, and ultimately helps you avoid them with easy-to-follow recipes. It is a valuable resource that can greatly aid programmers, code reviewers, architects, and students in improving their code skills and existing systems.

What You Need to Use This Book

In order to run the code samples, you will need a working environment like O’Reilly sandboxes or Replit. I encourage you to translate the code samples into your favorite programming language. Nowadays you can do it for free with artificial intelligence code generators. I’ve used tools such as GitHub Copilot, OpenAI Codex, Bard, ChatGPT, and many more to help me write this book’s code samples. Utilizing these tools has allowed me to use more than 25 different languages in this book even though I am not an expert in many of them.

About the Author

Maximiliano Contieri has been working in the software industry for 25 years and also teaching at the university at the same time. He's been writing about clean code, refactoring and code smells for three years, writing a couple of articles per week on many popular blogging platforms. He is a declarative and behavioral code fan and relies on software fundamentals to build elegant and robust solutions.