Refactoring Improving The Design Of Existing Code

As the application of object technology--particularly the Java programming language--has become commonplace, a new problem has emerged to confront the software development community. Significant numbers of poorly designed programs have been created by less-experienced developers, resulting in applications that are inefficient and hard to maintain and extend. Increasingly, software system professionals are discovering just how difficult it is to work with these inherited, "non-optimal" applications. For several years, expert-level object programmers have employed a growing collection of techniques to improve the structural integrity and performance of such existing software programs. Referred to as "refactoring," these practices have remained in the domain of experts because no attempt has been made to transcribe the lore into a form that all developers could use. . .until now. In Refactoring: Improving the Design of Existing Code, renowned object technology mentor Martin Fowler breaks new ground, demystifying these master practices and demonstrating how software practitioners can realize the significant benefits of this new process. With proper training a skilled system designer can take a bad design and rework it into well-designed, robust code. In this book, Martin Fowler shows you where opportunities for refactoring typically can be found, and how to go about reworking a bad design into a good one. Each refactoring step is simple--seemingly too simple to be worth doing. Refactoring may involve moving a field from one class to another, or pulling some code out of a method to turn it into its own method, or even pushing some code up or down a hierarchy. While these individual steps may seem elementary, the cumulative effect of such small changes can radically improve the design. Refactoring is a proven way to prevent software decay. In addition to discussing the various techniques of refactoring, the author provides a detailed catalog of more than seventy proven refactorings with helpful pointers that teach you when to apply them; step-by-step instructions for applying each refactoring; and an example illustrating how the refactoring works. The illustrative examples are written in Java, but the ideas are applicable to any object-oriented programming language.

Refactoring is gaining momentum amongst the object oriented programming community. It can transform the internal dynamics of applications and has the capacity to transform bad code into good code. This book offers an introduction to refactoring.

Martin Fowler’s guide to reworking bad code into well-structured code Refactoring improves the design of existing code and enhances software maintainability, as well as making existing code easier to understand. Original Agile Manifesto signer and software development thought leader, Martin Fowler, provides a catalog of refactorings that explains why you should refactor; how to recognize code that needs refactoring; and how to actually do it successfully, no matter what language you use. Refactoring principles: understand the process and general principles of refactoring Code smells: recognize “bad smells” in code that signal opportunities to refactor Application improvement: quickly apply useful refactorings to make a program easier to comprehend and change Building tests: writing good tests increases a programmer’s effectiveness Moving features: an important part of refactoring is moving elements between contexts Data structures: a collection of refactorings to organize data, an important role in programs Conditional Logic: use refactorings to make conditional sections easier to understand APIs: modules and their functions are the building blocks of our software, and APIs are the joints that we use to plug them together Inheritance: it is both very useful and easy to misuse, and it’s often hard to see the misuse until it’s in the rear-view mirror---refactorings can fix the misuse Examples are written in JavaScript, but you shouldn’t find it difficult to adapt the refactorings to whatever language you are currently using as they look mostly the same in different languages. "Whenever you read [Refactoring], it’s time to read it again. And if you haven’t read it yet, please do before writing another line of code." –David Heinemeier Hansson, Creator of Ruby on Rails, Founder & CTO at Basecamp “Any fool can write code that a computer can understand. Good programmers write code that humans can understand.” –M. Fowler (1999)

The Definitive Refactoring Guide, Fully Revamped for Ruby With refactoring, programmers can transform even the most chaotic software into well-designed systems that are far easier to evolve and maintain. What’s more, they can do it one step at a time, through a series of simple, proven steps. Now, there’s an authoritative and extensively updated version of Martin Fowler’s classic refactoring book that utilizes Ruby examples and idioms throughout–not code adapted from Java or any other environment. The authors introduce a detailed catalog of more than 70 proven Ruby refactorings, with specific guidance on when to apply each of them, step-by-step instructions for using them, and example code illustrating how they work. Many of the authors’ refactorings use powerful Ruby-specific features, and all code samples are available for download. Leveraging Fowler’s original concepts, the authors show how to perform refactoring in a controlled, efficient, incremental manner, so you methodically improve your code’s structure without introducing new bugs. Whatever your role in writing or maintaining Ruby code, this book will be an indispensable resource. This book will help you Understand the core principles of refactoring and the reasons for doing it Recognize “bad smells” in your Ruby code Rework bad designs into well-designed code, one step at a time Build tests to make sure your refactorings work properly Understand the challenges of refactoring and how they can be overcome Compose methods to package code properly Move features between objects to place responsibilities where they fit best Organize data to make it easier to work with Simplify conditional expressions and make more effective use of polymorphism Create interfaces that are easier to understand and use Generalize more effectively Perform larger refactorings that transform entire software systems and may take months or years Successfully refactor Ruby on Rails code

In 1994, Design Patterns changed the landscape of object-oriented development by introducing classic solutions to recurring design problems. In 1999, Refactoring revolutionized design by introducing an effective process for improving code. With the highly anticipated Refactoring to Patterns, Joshua Kerievsky has changed our approach to design by forever uniting patterns with the evolutionary process of refactoring. This book introduces the theory and practice of pattern-directed refactorings: sequences of low-level refactorings that allow designers to safely move designs to, towards, or away from pattern implementations. Using code from real-world projects, Kerievsky documents the thinking and steps underlying over two dozen pattern-based design transformations. Along the way he offers insights into pattern differences and how to implement patterns in the simplest possible ways. Coverage includes: A catalog of twenty-seven pattern-directed refactorings, featuring real-world code examples Descriptions of twelve design smells that indicate the need for this book’s refactorings General information and new insights about patterns and refactoring Detailed implementation mechanics: how low-level refactorings are combined to implement high-level patterns Multiple ways to implement the same pattern–and when to use each Practical ways to get started even if you have little experience with patterns or refactoring Refactoring to Patterns reflects three years of refinement and the insights of more than sixty software engineering thought leaders in the global patterns, refactoring, and agile development communities. Whether you’re focused on legacy or “greenfield” development, this book will make you a better software designer by helping you learn how to make important design changes safely and effectively.

Many businesses and organizations depend on older high-value PHP software that risks abandonment because it is impossible to maintain. The reasons for this may be that the software is not well designed; there is only one developer (the one who created the system) who can develop it because he didn’t use common design patterns and documentation; or the code is procedural, not object-oriented. With this book, you’ll learn to identify problem code and refactor it to create more effective applications using test-driven design.