Agile has become today's dominant software development paradigm, but Agile methods remain difficult to measure and improve. Essential Skills for the Agile Developer fills this gap from the bottom up, teaching proven techniques for assessing and optimizing both individual and team Agile practices. Written by four principals of Net Objectives-one of the world's leading Agile training and consulting firms-this book reflects unsurpassed experience helping organizations transition to Agile. It focuses on the specific actions and insights that can deliver the greatest design and programming…mehr
Agile has become today's dominant software development paradigm, but Agile methods remain difficult to measure and improve. Essential Skills for the Agile Developer fills this gap from the bottom up, teaching proven techniques for assessing and optimizing both individual and team Agile practices. Written by four principals of Net Objectives-one of the world's leading Agile training and consulting firms-this book reflects unsurpassed experience helping organizations transition to Agile. It focuses on the specific actions and insights that can deliver the greatest design and programming improvements with the least investment. The authors reveal key factors associated with successful Agile projects and offer practical ways to measure them. Through actual examples, they address principles, attitudes, habits, technical practices, and design considerations-and above all, show how to bring all these together to deliver higher-value software. Using the authors' techniques, managers and teams can optimize the whole: the whole organization and the whole product across its entire lifecycle. Essential Skills for the Agile Developer shows how to Program by intention Separate use from construction Consider testability before writing code Avoid over- and under-design Succeed with Acceptance Test Driven Development (ATDD) Minimize complexity and rework Use encapsulation more effectively and systematically Know when and how to use inheritance Prepare for change more successfully Perform continuous integration more successfully Master powerful best practices for design and refactoring
Alan Shalloway, founder and CEO of Net Objectives, is a renowned thought leader, trainer, and coach in Lean, Kanban, product portfolio management, Scrum, and agile design. His books include Lean-Agile Software Development (Addison-Wesley, 2009), Lean-Agile Pocket Guide For Scrum Teams (Lean-Agile Press, 2009), and both editions of Design Patterns Explained (Addison-Wesley, 2001 and 2004). Scott Bain, senior consultant at Net Objectives, is a 35+-year veteran in software development, engineering, and design. He authored the Jolt award-winning book Emergent Design (Addison-Wesley, 2008). Ken Pugh, a fellow consultant at Net Objectives, helps companies move to Lean-Agility through training and coaching. His books include Lean-Agile Acceptance Test Driven Development (Addison-Wesley, 2011) and the Jolt Award-winner Prefactoring (O’Reilly, 2005). Amir Kolsky is a senior consultant, coach, and trainer for Net Objectives with more than 25 years of experience.
Inhaltsangabe
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 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
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 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
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