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Refactoring: Ruby Edition, Rough Cuts

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Description

  • Copyright 2010
  • Dimensions: 7 X 9-1/8
  • Pages: 480
  • Edition: 1st
  • Rough Cuts
  • ISBN-10: 0-321-60419-9
  • ISBN-13: 978-0-321-60419-4

This is a working draft of a pre-release book. It is available before the published date as part of the Rough Cuts service.

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

Sample Content

Table of Contents

Foreword . . . xiii

Preface . . . xv

Acknowledgments . . . xx

About the Authors . . . xxii

Chapter 1: Refactoring, a First Example . . . 1

The Starting Point . . . 2

The First Step in Refactoring . . . 6

Decomposing and Redistributing the Statement Method . . . 7

Replacing the Conditional Logic on Price Code with Polymorphism . . . 32

Final Thoughts . . . 50

Chapter 2: Principles in Refactoring . . . 51

Where Did Refactoring Come From? . . . 51

Defining Refactoring . . . 52

Why Should You Refactor? . . . 54

When Should You Refactor? . . . 57

Why Refactoring Works . . . 60

What Do I Tell My Manager? . . . 61

Indirection and Refactoring . . . 61

Problems with Refactoring . . . 63

Refactoring and Design. . . . 67

It Takes A While to Create Nothing . . . 69

Refactoring and Performance . . . 70

Optimizing a Payroll System . . . 71

Chapter 3: Bad Smells in Code . . . 73

Duplicated Code . . . 74

Long Method . . . 74

Large Class . . . 76

Long Parameter List . . . 76

Divergent Change . . . 77

Shotgun Surgery . . . 78

Feature Envy . . . 78

Data Clumps . . . 79

Primitive Obsession . . . 79

Case Statements . . . 80

Parallel Inheritance Hierarchies . . . 81

Lazy Class . . . 81

Speculative Generality . . . 81

Temporary Field . . . 82

Message Chains . . . 82

Middle Man . . . 83

Inappropriate Intimacy . . . 83

Alternative Classes with Different Interfaces . . . 83

Incomplete Library Class . . . 84

Data Class . . . 84

Refused Bequest . . . 84

Comments . . . 85

Metaprogramming Madness . . . 86

Disjointed API . . . 86

Repetitive Boilerplate . . . 86

Chapter 4: Building Tests . . . 87

The Value of Self-Testing Code . . . 87

The Test::Unit Testing Framework . . . 88

Developer and Quality Assurance Tests . . . 91

Adding More Tests . . . 92

Chapter 5: Toward a Catalog of Refactorings . . . 97

Format of the Refactorings . . . 97

Finding References . . . 99

Chapter 6: Composing Methods . . . 101

Extract Method . . . 102

Inline Method . . . 108

Inline Temp . . . 110

Replace Temp with Query. . . 111

Replace Temp with Chain . . . 114

Introduce Explaining Variable . . . 117

Split Temporary Variable . . . 12

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