Bill Wagner is one of the world’s foremost C# developers, a member of the ECMA C# Standards Committee, and author of all three editions of Effective C#. He is president of the Humanitarian Toolbox, has been awarded Microsoft Regional Director and .NET MVP for 11 years, and was recently appointed to the .NET Foundation Advisory Council. Wagner has helped companies ranging from start-ups to enterprises to improve development processes and grow development teams. Now a member of Microsoft’s .NET Core content team, he creates developer learning materials on the C# language and .NET Core.

Introduction xi

Chapter 1: Working with Data Types 1

Item 1: Use Properties Instead of Accessible Data Members 1

Item 2: Prefer Implicit Properties for Mutable Data 8

Item 3: Prefer Immutability for Value Types 12

Item 4: Distinguish Between Value Types and Reference Types 18

Item 5: Ensure That 0 Is a Valid State for Value Types 24

Item 6: Ensure That Properties Behave Like Data 28

Item 7: Limit Type Scope by Using Tuples 34

Item 8: Define Local Functions on Anonymous Types 39

Item 9: Understand the Relationships Among the Many Different Concepts of Equality 45

Item 10: Understand the Pitfalls of GetHashCode() 54

Chapter 2: API Design 61

Item 11: Avoid Conversion Operators in Your APIs 61

Item 12: Use Optional Parameters to Minimize Method Overloads 65

Item 13: Limit Visibility of Your Types 69

Item 14: Prefer Defining and Implementing Interfaces to Inheritance 73

Item 15: Understand How Interface Methods Differ from Virtual Methods 82

Item 16: Implement the Event Pattern for Notifications 86

Item 17: Avoid Returning References to Internal Class Objects 93

Item 18: Prefer Overrides to Event Handlers 97

Item 19: Avoid Overloading Methods Defined in Base Classes 100

Item 20: Understand How Events Increase Runtime Coupling Among Objects 104

Item 21: Declare Only Nonvirtual Events 107

Item 22: Create Method Groups That Are Clear, Minimal, and Complete 113

Item 23: Give Partial Classes Partial Methods for Constructors, Mutators, and Event Handlers 120

Item 24: Avoid ICloneable Because It Limits Your Design Choices 125

Item 25: Limit Array Parameters to params Arrays 129

Item 26: Enable Immediate Error Reporting in Iterators and Async Methods Using Local Functions 134

Chapter 3: Task-Based Asynchronous Programming 139

Item 27: Use Async Methods for Async Work 139

Item 28: Never Write async void Methods 143

Item 29: Avoid Composing Synchronous and Asynchronous Methods 149

Item 30: Use Async Methods to Avoid Thread Allocations and Context Switches 154

Item 31: Avoid Marshalling Context Unnecessarily 156

Item 32: Compose Asynchronous Work Using Task Objects 160

Item 33: Consider Implementing the Task Cancellation Protocol 166

Item 34: Cache Generalized Async Return Types 173

Chapter 4: Parallel Processing 177

Item 35: Learn How PLINQ Implements Parallel Algorithms 177

Item 36: Construct Parallel Algorithms with Exceptions in Mind 189

Item 37: Use the Thread Pool Instead of Creating Threads 195

Item 38: Use BackgroundWorker for Cross-Thread Communication 201

Item 39: Understand Cross-Thread Calls in XAML Environments 205

Item 40: Use lock() as Your First Choice for Synchronization 214

Item 41: Use the Smallest Possible Scope for Lock Handles 221

Item 42: Avoid Calling Unknown Code in Locked Sections 225

Chapter 5: Dynamic Programming 229

Item 43: Understand the Pros and Cons of Dynamic Typing 229

Item 44: Use Dynamic Typing to Leverage the Runtime Type of Generic Type Parameters 238

Item 45: Use DynamicObject or IDynamicMetaObjectProvider for Data-Driven Dynamic Types 242

Item 46: Understand How to Use the Expression API 253

Item 47: Minimize Dynamic Objects in Public APIs 259

Chapter 6: Participate in the Global C# Community 267

Item 48: Seek the Best Answer, Not the Most Popular Answer 267

Item 49: Participate in Specs and Code 269

Item 50: Consider Automating Practices with Analyzers 271

Index 273