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Your class library works, but could it be better? Refactoring: Improving the Design of Existing Code shows how refactoring can make object-oriented code simpler and easier to maintain. Today refactoring requires considerable design know-how, but once tools become available, all programmers should be able to improve their code using refactoring techniques.

Besides an introduction to refactoring, this handbook provides a catalog of dozens of tips for improving code. The best thing about Refactoring is its remarkably clear presentation, along with excellent nuts-and-bolts advice, from object expert Martin Fowler. The author is also an authority on software patterns and UML, and this experience helps make this a better book, one that should be immediately accessible to any intermediate or advanced object-oriented developer. (Just like patterns, each refactoring tip is presented with a simple name, a "motivation," and examples using Java and UML.)

Early chapters stress the importance of testing in successful refactoring. (When you improve code, you have to test to verify that it still works.) After the discussion on how to detect the "smell" of bad code, readers get to the heart of the book, its catalog of over 70 "refactorings"--tips for better and simpler class design. Each tip is illustrated with "before" and "after" code, along with an explanation. Later chapters provide a quick look at refactoring research.

Like software patterns, refactoring may be an idea whose time has come. This groundbreaking title will surely help bring refactoring to the programming mainstream. With its clear advice on a hot new topic, Refactoring is sure to be essential reading for anyone who writes or maintains object-oriented software. --Richard Dragan

Topics Covered: Refactoring, improving software code, redesign, design tips, patterns, unit testing, refactoring research, and tools.

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 Software, 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.

What Is This Book About?
This book is about the marriage of refactoring—the process of improving the design of existing code—with patterns, the classic solutions to recurring design problems. Refactoring to Patterns suggests that using patterns to improve an existing design is better than using patterns early in a new design. This is true whether code is years old or minutes old. We improve designs with patterns by applying sequences of low-level design transformations, known as refactorings.

What Are the Goals of This Book?
This book was written to help you:

Understand how to combine refactoring and patterns
Improve the design of existing code with pattern-directed refactorings
Identify areas of code in need of pattern-directed refactorings
Learn why using patterns to improve existing code is better than using patterns early in a new design
To achieve these goals, this book includes the following features:

A catalog of 27 refactorings
Examples based on real-world code, not the toy stuff
Pattern descriptions, including real-world pattern examples
A collection of smells (i.e., problems) that indicate the need for pattern-directed refactorings
Examples of different ways to implement the same pattern
Advice for when to refactor to, towards, or away from patterns
To help individuals or groups learn the 27 refactorings in the book, you'll find a suggested study sequence on the inside back cover of the book.

Who Should Read This Book?

This book is for object-oriented programmers engaged in or interested in improving the design of existing code. Many of these programmers use patterns and/or practice refactoring but have never implemented patterns by refactoring; others know little about refactoring and patterns and would like to learn more.

This book is useful for both greenfield development, in which you are writing a new system or feature from scratch, and legacy development, in which you are mostly maintaining a legacy system.

What Background Do You Need?
This book assumes you are familiar with design concepts like tight coupling and loose coupling as well as object-oriented concepts like inheritance, polymorphism, encapsulation, composition, interfaces, abstract and concrete classes, abstract and static methods, and so forth.

I use Java examples in this book. I find that Java tends to be easy for most object-oriented programmers to read. I've gone out of my way to not use fancy Java features, so whether you code in C++, C#, Visual Basic .NET, Python, Ruby, Smalltalk, or some other object-oriented language, you ought to be able to understand the Java code in this book.

This book is closely tied to Martin Fowler's classic book Refactoring F. It contains references to low-level refactorings, such as:

Extract Method
Extract Interface
Extract Superclass
Extract Subclass
Pull Up Method
Move Method
Rename Method

Refactoring also contains references to more sophisticated refactorings, such as:

Replace Inheritance with Delegation
Replace Conditional with Polymorphism
Replace Type Code with Subclasses

To understand the pattern-directed refactorings in this book, you don't need to know every refactoring listed above. Instead, you can follow the example code that illustrates how the listed refactorings are implemented. However, if you want to get the most out of this book, I do recommend that you have Refactoring close by your side. It's an invaluable refactoring resource, as well as a useful aid for understanding this book.

The patterns I write about come from the classic book Design Patterns DP, as well as from authors such as Kent Beck, Bobby Woolf, and myself. These are patterns that my colleagues and I have refactored to, towards, or away from on real-world projects. By learning the art of pattern-directed refactorings, you'll understand how to refactor to, towards, or away from patterns not mentioned in this book.

You don't need expert knowledge of these patterns to read this book, though some knowledge of patterns is useful. To help you understand the patterns I've written about, this book includes brief pattern summaries, UML sketches of patterns, and many example implementations of patterns. To get a more detailed understanding of the patterns, I recommend that you study this book in conjunction with the patterns literature I reference.

This book uses UML 2.0 diagrams. If you don't know UML very well, you're in good company. I know the basics. While writing this book, I kept the third edition of Fowler's UML Distilled Fowler, UD close by my side and referred to it often.

Your class library works, but could it be better? Refactoring: Improving the Design of Existing Code shows how refactoring can make object-oriented code simpler and easier to maintain. Today refactoring requires considerable design know-how, but once tools become available, all programmers should be able to improve their code using refactoring techniques.

Besides an introduction to refactoring, this handbook provides a catalog of dozens of tips for improving code. The best thing about Refactoring is its remarkably clear presentation, along with excellent nuts-and-bolts advice, from object expert Martin Fowler. The author is also an authority on software patterns and UML, and this experience helps make this a better book, one that should be immediately accessible to any intermediate or advanced object-oriented developer. (Just like patterns, each refactoring tip is presented with a simple name, a "motivation," and examples using Java and UML.)

Early chapters stress the importance of testing in successful refactoring. (When you improve code, you have to test to verify that it still works.) After the discussion on how to detect the "smell" of bad code, readers get to the heart of the book, its catalog of over 70 "refactorings"--tips for better and simpler class design. Each tip is illustrated with "before" and "after" code, along with an explanation. Later chapters provide a quick look at refactoring research.

Like software patterns, refactoring may be an idea whose time has come. This groundbreaking title will surely help bring refactoring to the programming mainstream. With its clear advice on a hot new topic, Refactoring is sure to be essential reading for anyone who writes or maintains object-oriented software. --Richard Dragan

Topics Covered: Refactoring, improving software code, redesign, design tips, patterns, unit testing, refactoring research, and tools.

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 Software, 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, Refactoring: Improving the Design of Existing Software 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.

“Wow, what a compendium of great information and how-to’s! I am so impressed! Elliotte’s written a book whose title comes nowhere near to
doing it justice. Covering much more than just refactoring, this book explains how to do it right the first time around, in a clear and lucid
voice. Harold obviously knows his stuff. A must-read!”
—Howard Katz, Proprietor, Fatdog Software

“After working with people who require the skills and tools necessary to continually improve the quality and security of their applications, I
have discovered a missing link. The ability to rebuild and recode applications is a key area of weakness for web designers and web application
developers alike. By building refactoring into the development process, incremental changes to the layout or internals efficiently averts a total
rewrite or complete make-over. This is a fantastic book for anyone who needs to rebuild, recode, or refactor the web.”
—Andre Gironda, tssci-security.com

“Elliotte’s book provides a rare collection of hints and tricks that will vastly improve the quality of web pages. Virtually any serious HTML
developer, new or tenured, in any size organization will reap tremendous benefit from implementing even a handful of his suggestions.”
—Matt Lavallee, Development Manager, MLS Property Information Network, Inc.

Like any other software system, Web sites gradually accumulate “cruft” over time. They slow down. Links break. Security and compatibility problems mysteriously appear. New features don’t integrate seamlessly. Things just don’t work as well. In an ideal world, you’d rebuild from scratch. But you can’t: there’s no time or money for that. Fortunately, there’s a solution: You can refactor your Web code using easy, proven techniques, tools, and recipes adapted from the world of software development.

In Refactoring HTML, Elliotte Rusty Harold explains how to use refactoring to improve virtually any Web site or application. Writing for programmers and non-programmers alike, Harold shows how to refactor for better reliability, performance, usability, security, accessibility, compatibility, and even search engine placement. Step by step, he shows how to migrate obsolete code to today’s stable Web standards, including XHTML, CSS, and REST—and eliminate chronic problems like presentation-based markup, stateful applications, and “tag soup.”

The book’s extensive catalog of detailed refactorings and practical “recipes for success” are organized to help you find specific solutions fast, and get maximum benefit for minimum effort. Using this book, you can quickly improve site performance now—and make your site far easier to enhance, maintain, and scale for years to come.

Topics covered include

• Recognizing the “smells” of Web code that should be refactored
• Transforming old HTML into well-formed, valid XHTML, one step at a time
• Modernizing existing layouts with CSS
• Updating old Web applications: replacing POST with GET, replacing old contact forms, and refactoring JavaScript
• Systematically refactoring content and links
• Restructuring sites without changing the URLs your users rely upon

This book will be an indispensable resource for Web designers, developers, project managers, and anyone who maintains or updates existing sites. It will be especially helpful to Web professionals who learned HTML years ago, and want to refresh their knowledge with today’s standards-compliant best practices.
This book will be an indispensable resource for Web designers, developers, project managers, and anyone who maintains or updates existing sites. It will be especially helpful to Web professionals who learned HTML years ago, and want to refresh their knowledge with today’s standards-compliant best practices.

Automated testing is a cornerstone of agile development. An effective testing strategy will deliver new functionality more aggressively, accelerate user feedback, and improve quality. However, for many developers, creating effective automated tests is a unique and unfamiliar challenge.

xUnit Test Patterns is the definitive guide to writing automated tests using xUnit, the most popular unit testing framework in use today. Agile coach and test automation expert Gerard Meszaros describes 68 proven patterns for making tests easier to write, understand, and maintain. He then shows you how to make them more robust and repeatable--and far more cost-effective.

Loaded with information, this book feels like three books in one. The first part is a detailed tutorial on test automation that covers everything from test strategy to in-depth test coding. The second part, a catalog of 18 frequently encountered "test smells," provides trouble-shooting guidelines to help you determine the root cause of problems and the most applicable patterns. The third part contains detailed descriptions of each pattern, including refactoring instructions illustrated by extensive code samples in multiple programming languages.

Topics covered include

• Writing better tests--and writing them faster
• The four phases of automated tests: fixture setup, exercising the system under test, result verification, and fixture teardown
• Improving test coverage by isolating software from its environment using Test Stubs and Mock Objects
• Designing software for greater testability
• Using test "smells" (including code smells, behavior smells, and project smells) to spot problems and know when and how to eliminate them
• Refactoring tests for greater simplicity, robustness, and execution speed

This book will benefit developers, managers, and testers working with any agile or conventional development process, whether doing test-driven development or writing the tests last. While the patterns and smells are especially applicable to all members of the xUnit family, they also apply to next-generation behavior-driven development frameworks such as RSpec and JBehave and to other kinds of test automation tools, including recorded test tools and data-driven test tools such as Fit and FitNesse.

Visual Summary of the Pattern Language
Foreword
Preface
Acknowledgments
Introduction
Refactoring a Test
PART I: The Narratives
Chapter 1 A Brief Tour
Chapter 2 Test Smells
Chapter 3 Goals of Test Automation
Chapter 4 Philosophy of Test Automation
Chapter 5 Principles of Test Automation
Chapter 6 Test Automation Strategy
Chapter 7 xUnit Basics
Chapter 8 Transient Fixture Management
Chapter 9 Persistent Fixture Management
Chapter 10 Result Verification
Chapter 11 Using Test Doubles
Chapter 12 Organizing Our Tests
Chapter 13 Testing with Databases
Chapter 14 A Roadmap to Effective Test Automation
PART II: The Test Smells
Chapter 15 Code Smells
Chapter 16 Behavior Smells
Chapter 17 Project Smells
PART III: The Patterns
Chapter 18 Test Strategy Patterns
Chapter 19 xUnit Basics Patterns
Chapter 20 Fixture Setup Patterns
Chapter 21 Result Verification Patterns
Chapter 22 Fixture Teardown Patterns
Chapter 23 Test Double Patterns
Chapter 24 Test Organization Patterns
Chapter 25 Database Patterns
Chapter 26 Design-for-Testability Patterns
Chapter 27 Value Patterns
PART IV: Appendixes
Appendix A Test Refactorings
Appendix B xUnit Terminology
Appendix C xUnit Family Members
Appendix D Tools
Appendix E Goals and Principles
Appendix F Smells, Aliases, and Causes
Appendix G Patterns, Aliases, and Variations
Glossary
References
Index

What can you do when database performance doesn't meet expectations? Before you turn to expensive hardware upgrades to solve the problem, reach for this book. Refactoring SQL Applications provides a set of tested options for making code modifications to dramatically improve the way your database applications function. Backed by real-world examples, you'll find quick fixes for simple problems, in-depth answers for more complex situations, and complete solutions for applications with extensive problems. Learn to:

• Determine if and where you can expect performance gains
• Apply quick fixes, such as limiting calls to the database in stored functions and procedures
• Refactor tasks, such as replacing application code by a stored procedure, or replacing iterative, procedural statements with sweeping SQL statements
• Refactor flow by increasing parallelism and switching business-inducted processing from synchronous to asynchronous
• Refactor design using schema extensions, regular views, materialized views, partitioning, and more
• Compare before and after versions of a program to ensure you get the same results once you make modifications

Refactoring SQL Applications teaches you to recognize and assess code that needs refactoring, and to understand the crucial link between refactoring and performance. If and when your application bogs down, this book will help you get it back up to speed.

In Refactoring HTML, Elliotte Rusty Harold explains how to use refactoring to improve virtually any Web site or application. Writing for programmers and non-programmers alike, Harold shows how to refactor for better reliability, performance, usability, security, accessibility, compatibility, and even search engine placement. Step by step, he shows how to migrate obsolete code to today's stable Web standards, including XHTML, CSS, and REST-and eliminate chronic problems like presentation-based markup, stateful applications, and "tag soup."

The book's extensive catalog of detailed refactorings and practical "recipes for success" are organized to help you find specific solutions fast, and get maximum benefit for minimum effort. Using this book, you can quickly improve site performance now-and make your site far easier to enhance, maintain, and scale for years to come.

Topics covered include

- Recognizing the "smells" of Web code that should be refactored
- Transforming old HTML into well-formed, valid XHTML, one step at a time
- Modernizing existing layouts with CSS
- Updating old Web applications: replacing POST with GET, replacing old contact forms, and refactoring JavaScript
- Systematically refactoring content and links
- Restructuring sites without changing the URLs your users rely upon

This book will be an indispensable resource for Web designers, developers, project managers, and anyone who maintains or updates existing sites. It will be especially helpful to Web professionals who learned HTML years ago, and want to refresh their knowledge with today-s standards-compliant best practices.
This book will be an indispensable resource for Web designers, developers, project managers, and anyone who maintains or updates existing sites. It will be especially helpful to Web professionals who learned HTML years ago, and want to refresh their knowledge with today-s standards-compliant best practices.