Implementation Patterns

Preface xv

Chapter 1: Introduction 1

Tour Guide 3

And Now... 4

Chapter 2: Patterns 5

Chapter 3: A Theory of Programming 9

Values 10

Principles 13

Conclusion 18

Chapter 4: Motivation 19

Chapter 5: Class 21

Class 22

Simple Superclass Name 23

Qualified Subclass Name 24

Abstract Interface 24

Interface 26

Abstract Class 26

Versioned Interface 27

Value Object 28

Specialization 31

Subclass 32

Implementor 34

Inner Class 34

Instance-Specific Behavior 36

Conditional 36

Delegation 38

Pluggable Selector 40

Anonymous Inner Class 41

Library Class 41

Conclusion 42

Chapter 6: State 43

State 44

Access 45

Direct Access 46

Indirect Access 47

Common State 47

Variable State 48

Extrinsic State 50

Variable 50

Local Variable 51

Field 52

Parameter 53

Collecting Parameter 55

Optional Parameter 56

Var Args 56

Parameter Object 57

Constant 58

Role-Suggesting Name 58

Declared Type 60

Initialization 61

Eager Initialization 61

Lazy Initialization 62

Conclusion 62

Chapter 7: Behavior 63

Control Flow 64

Main Flow 64

Message 65

Choosing Message 65

Double Dispatch 66

Decomposing (Sequencing) Message 67

Reversing Message 67

Inviting Message 68

Explaining Message 69

Exceptional Flow 70

Guard Clause 70

Exception 72

Checked Exceptions 72

Exception Propagation 73

Conclusion 73

Chapter 8: Methods 75

Composed Method 77

Intention-Revealing Name 79

Method Visibility 80

Method Object 82

Overridden Method 83

Overloaded Method 83

Method Return Type 84

Method Comment 85

Helper Method 85

Debug Print Method 86

Conversion 87

Conversion Method 87

Conversion Constructor 88

Creation 88

Complete Constructor 89

Factory Method 90

Internal Factory 91

Collection Accessor Method 91

Boolean Setting Method 93

Query Method 93

Equality Method 94

Getting Method 95

Setting Method 96

Safe Copy 97

Conclusion 98

Chapter 9: Collections 99

Metaphors 100

Issues 101

Interfaces 103

Implementations 107

Collections 110

Extending Collections 114

Conclusion 115

Chapter 10: Evolving Frameworks 117

Changing Frameworks without Changing Applications 117

Incompatible Upgrades 118

Encouraging Compatible Change 120

Conclusion 129

Appendix A: Performance Measurement 131

Example 131

API 132

Implementation 133

MethodTimer 134

Canceling Overhead 136

Tests 136

Conclusion 142

Bibliography 145

General Programming 145

Philosophy 147

Java 148

Index 149