Series Foreword xvii Preface xxi Acknowledgments xxiii About the Authors xxv Part I: The Core Trim Tabs 1 Chapter 1: Programming by Intention 3 Programming by Intention: A Demonstration 3 Advantages 6 Summary 18 Chapter 2: Separate Use from Construction 21 An Important Question to Ask 21 Perspectives 22 Timing Your Decisions 30 Overloading and C++ 31 Validating This for Yourself 32 Summary 33 Chapter 3: Define Tests Up Front 35 A Trim Tab: Testing and Testability 35 What Is Testing? 35 Testability and Code Quality 36 Case Study: Testability 37 A Reflection on Up-Front Testing 39 Summary 44 Chapter 4: Shalloway''s Law and Shalloway''s Principle 45 Types of Redundancy 46 Redefining Redundancy 46 Other Types of Redundancy 47 The Role of Design Patterns in Reducing Redundancy 48 Few Developers Spend a Lot of Time Fixing Bugs 48 Redundancy and Other Code Qualities 50 Summary 52 Chapter 5: Encapsulate That! 53 Unencapsulated Code: The Sabotage of the Global Variable 53 Encapsulation of Member Identity 54 Self-Encapsulating Members 56 Preventing Changes 58 The Difficulty of Encapsulating Reference Objects 59 Breaking Encapsulation with Get() 62 Encapsulation of Object Type 64 Encapsulation of Design 67 Encapsulation on All Levels 69 Practical Advice: Encapsulate Your Impediments 69 Summary 72 Chapter 6: Interface-Oriented Design 75 Design to Interfaces 75 Definition of Interface 75 Interface Contracts 76 Separating Perspectives 77 Mock Implementations of Interfaces 79 Keep Interfaces Simple 79 Avoids Premature Hierarchies 80 Interfaces and Abstract Classes 81 Dependency Inversion Principle 82 Polymorphism in General 83 Not for Every Class 84 Summary 84 Chapter 7: Acceptance Test--Driven Development (ATDD) 85 Two Flows for Development 85 Acceptance Tests 88 An Example Test 88 Implementing the Acceptance Tests 90 An Exercise 95 What to Do If the Customer Won''t Tell You 95 Summary 96 Part II: General Attitudes 97 Chapter 8: Avoid Over- and Under-Design 99 A Mantra for Development 99 The Pathologies of Code Qualities 100 Avoid Over- and Under-Design 101 Minimize Complexity and Rework 102 Never Make Your Code Worse/Only Degrade Your Code Intentionally 102 Keep Your Code Easy to Change, Robust, and Safe to Change 103 A Strategy for Writing Modifiable Code in a Non-Object-Oriented or Legacy System 103 Summary 107 Chapter 9: Continuous Integration 109 Branching the Source Code 109 The Merge-Back 115 Test-Driven Development and Merge Cost 117 Continuous Integration 119 Continuous Integration Servers 121 Summary 122 Part III: Design Issues 125 Chapter 10: Commonality and Variability Analysis 127 Using Nouns and Verbs as a Guide: Warning, Danger Ahead! 127 What Is the Real Problem? 130 What We Need to Know 131 Commonality and Variability Analysis 132 A New Paradigm for Finding Objects 134 The Analysis Matrix: A Case Study 136 Summary 145 Chapter 11: Refactor to the Open-Closed 147 The Open-Closed Principle 147 Refactoring 154 Summary 161 Chapter 12: Needs versus Capabilities Interfaces 163 The Law of Demeter 163 Coupling, Damned Coupling, and Dependencies 166 The Ideal Separation: Needs Interfaces and Capabilities Interfaces 168 Back to the Law of Demeter 169 Summary 171 Chapter 13: When and How to Use Inheritance 173 The Gang of Four 173 Initial Vectors, Eventual Results 176 Favoring Delegation 178 The Use of Inheritance versus Delegation 180 Uses of Inheritance 181 Scalability 183 Applying the Lessons from the Gang of Four to Agile Development 184 Testing Issues 185 There''s More 187 Part IV: Appendixes 189 Appendix A: Overview of the Unified Modeling Language (UML) 191 What Is the UML? 191 The Class Diagram 192 Sequence Diagram 198 Summary 200 Appendix B: Code Qualities 201 Christmas-Tree Lights: An Analogy 201 Cohesion 204 Coupling 205 Redundancy 207 Encapsulation 208 Appendix C: Encapsulating Primitives 211 Encapsulating Primitives in Abstract Data Types 211 Principles 212 Narrow the Contract 213 Expanding Abstract Data Types 214 Use Text as External Values 215 Enumerations Instead of Magic Values 217 Disadvantages 218 Summary 219 Index 221.