Design Patterns in .NET 6: Reusable Approaches in C# and F# for Object-Oriented Software Design. 3 Ed

Table of Contents....5

About the Author....15

About the Technical Reviewer....16

Introduction....17

Part I: Introduction....21

Chapter 1: The SOLID Design Principles....22

Single Responsibility Principle....22

Open-Closed Principle....25

Liskov Substitution Principle....32

Interface Segregation Principle....34

Parameter Object....39

Dependency Inversion Principle....40

Chapter 2: The Functional Perspective....44

Function Basics....44

Functional Literals in C#....46

Storing Functions in C#....47

Functional Literals in F#....49

Composition....51

Functional-Related Language Features....52

Part II: Creational Patterns....53

Chapter 3: Builder....55

Scenario....55

Simple Builder....58

Fluent Builder....59

Static Initialization....59

Communicating Intent....60

Nested Builder and Immutability....62

Composite Builder....63

Builder Marker Interfaces....67

Stepwise Builder (Wizard)....69

Builder Parameter....74

Builder Extension with Recursive Generics....76

Lazy Functional Builder....80

Builder-Decorator....83

Scoping Builder Method....86

DSL Construction in F#....87

Summary....88

Chapter 4: Factories....90

Scenario....90

Factory Method....92

Asynchronous Factory Method....93

Factory....94

Inner Factory....95

Physical Separation....96

Abstract Factory....96

Delegate Factories in IoC....100

Object Tracking and Bulk Replacements....102

Object Tracking....102

Bulk Modifications....104

Functional Factory....107

Summary....108

Chapter 5: Prototype....110

Deep vs. Shallow Copying....110

ICloneable Is Bad....111

Deep Copying via Copy Construction....113

Note on Record Classes....114

Deep Copying with a Special Interface....114

Deep Copying and Inheritance....115

Deep Copying Guidelines....119

Trivially Copyable Types....120

Arrays....120

Common Collection Types....121

MemberwiseClone Is Not Terrible....122

Summary....123

Serialization....124

Prototype Factory....126

Source Generators....127

Summary....128

Chapter 6: Singleton....129

Singleton by Convention....129

Classic Implementation....130

Lazy Loading and Thread Safety....131

Reusable Base Class....132

The Trouble with Singleton....133

Per-Thread Singleton....137

Ambient Context....138

Uses in the .NET Framework....142

Singletons and Inversion of Control....143

Monostate....144

Multiton....145

Summary....146

Part III: Structural Patterns....147

Chapter 7: Adapter....149

Scenario....149

Adapter....151

Adapter Temporaries....152

The Problem with Hashing....156

Property Adapter (Surrogate)....158

Generic Value Adapter....160

Adapter in Dependency Injection....168

Bidirectional Adapter....171

Adapters in the .NET Framework....172

Summary....173

Chapter 8: Bridge....174

Conventional Bridge....174

Dynamic Prototyping Bridge....178

Summary....181

Chapter 9: Composite....182

Grouping Graphic Objects....182

Neural Networks....185

Shrink Wrapping the Composite....188

Composite Specification....190

Summary....193

Chapter 10: Decorator....194

The Basics of Delegation....195

Points and Lines....197

Adapter-Decorator....200

Simulating Multiple Inheritance....200

Multiple Inheritance with Interfaces....201

Multiple Inheritance with Default Interface Members....204

Dynamic Decorator Composition....206

Decorator Cycle Policies....209

Static Decorator Composition....215

Functional Decorator....216

Summary....217

Chapter 11: Façade....219

Magic Squares....220

Building a Trading Terminal....225

An Advanced Terminal....226

Where’s the Façade?....228

IoC Modules....230

Summary....232

Chapter 12: Flyweight....233

User Names....233

Text Formatting....236

Using Flyweights for Interop....239

Summary....240

Chapter 13: Proxy....241

Protection Proxy....241

Property Proxy....243

Composite Proxy: SoA/AoS....246

Composite Proxy with Array-Backed Properties....249

Virtual Proxy....251

Communication Proxy....254

Dynamic Proxy for Logging....256

Composite Proxy....259

Summary....262

Chapter 14: Value Object....264

Two-Dimensional Point....265

Percentage Value....266

Units of Measure....268

Summary....270

Part IV: Behavioral Patterns....271

Chapter 15: Chain of Responsibility....272

Scenario....272

Method Chain....273

Broker Chain....276

Functional Chain of Responsibility....281

Summary....282

Chapter 16: Command....283

Scenario....283

Implementing the Command Pattern....284

Undo Operations....286

Composite Commands (aka Macros)....289

Functional Command....293

Queries and Command-Query Separation....295

Summary....295

Chapter 17: Interpreter....297

Integer Parsing....298

Numeric Expression Evaluator....299

Lexing....300

Parsing....302

Using Lexer and Parser....306

Interpretation in the Functional Paradigm....306

Transpiler....310

Summary....312

Chapter 18: Iterator....314

Array-Backed Properties....315

Let’s Make an Iterator....318

Improved Iteration....321

Iterator Specifics....323

Iterator Adapter....324

Composite Iteration....326

Summary....328

Chapter 19: Mediator....329

Chat Room....329

Mediator with Events....334

Introduction to MediatR....338

Service Bus as Mediator....340

Summary....341

Chapter 20: Memento....342

Bank Account....342

Undo and Redo....344

Memento and Command....347

Summary....348

Chapter 21: Null Object....350

Scenario....350

Intrusive Approaches....352

Nullable Virtual Proxy....353

Null Object....354

Null Object Singleton....355

Dynamic Null Object....356

Drawbacks....357

Summary....358

Chapter 22: Observer....359

Events....359

Weak Event Pattern....361

Event Streams....363

Property Observers....367

Basic Change Notification....367

Bidirectional Bindings....369

Property Dependencies....372

Views....378

Case Study: Quadratic Equation Solver....380

Circular Recalculation Limitations....382

Observable Collections....383

Observable LINQ....384

Declarative Subscriptions in Autofac....384

Summary....388

Chapter 23: State....389

State-Driven State Transitions....390

Enum-Based State Machine....393

Switch-Based State Machine....396

Encoding Transitions with Switch Expressions....398

State Machines with Stateless....400

Types, Actions, and Ignoring Transitions....401

Reentrancy Again....402

Hierarchical States....403

More Features....403

Concurrent State Machines....404

Implicit State Machines....405

Summary....405

Chapter 24: Strategy....407

Dynamic Strategy....407

Static Strategy....410

Equality and Comparison Strategies....412

Functional Strategy....414

Declarative Strategies....415

Summary....416

Chapter 25: Template Method....417

Game Simulation....417

Template Method Mixin....419

Functional Template Method....421

Summary....422

Chapter 26: Visitor....423

Intrusive Visitor....424

Reflective Visitor....425

Extension Methods?....428

Functional Reflective Visitor (C#)....430

Functional Reflective Visitor (F#)....432

Improvements....433

What Is Dispatch?....434

Dynamic Visitor....436

Classic Visitor....438

Abstract Classes and Virtual Methods....441

Reducing Boilerplate....443

Implementing an Additional Visitor....443

Type Checks Are Unavoidable....445

Acyclic Visitor....447

Visitable Null Object....449

Visitor Adapter....453

Reductions and Transforms....456

Functional Visitor in F#....460

Summary....461

Index....463

Implement design patterns in .NET 6 using the latest versions of the C# and F# languages. This book provides a comprehensive overview of the field of design patterns as they are used in today’s developer toolbox. In addition to the functional builder, asynchronous factory method, generic value adapter, and composite proxies, this new edition introduces topics such as Decorator Cycle Policies Functional Commands, a Transformer variation of the Visitor pattern, and factories that can perform Object Tracking and Bulk Replacement.Using the C# and F# programming languages, Design Patterns in .NET 6 explores the classic design pattern implementations and discusses the applicability and relevance of specific language features for implementing patterns. You will learn by example, reviewing scenarios where patterns are applicable. Former C# MVP and patterns expert Dmitri Nesteruk demonstrates possible implementations of patterns,discusses alternatives and pattern relationships, and illustrates the way that a dedicated refactoring tool (JetBrains Rider) can be used to implement design patterns with ease.

What You Will Learn

• Become familiar with the latest pattern implementations available in C# 10 and F# 6
• Know how to better reason about software architecture
• Understand the process of refactoring code to patterns
• Refer to researched and proven variations of patterns
• Study complete, self-contained examples, including many that cover advanced scenarios
• Use the latest versions of C# and Visual Studio/Rider/ReSharper

Who This Book Is For

 Developers who have some experience in the C# language and want to expand their comprehension of the art of programming by leveraging design approaches to solve modern problems