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

Table of Contents
About the Author
About the Technical Reviewer
Introduction
Chapter 1: The SOLID Design Principles
	Single Responsibility Principle
	Open-Closed Principle
	Liskov Substitution Principle
	Interface Segregation Principle
		Parameter Object
	Dependency Inversion Principle
Chapter 2: The Functional Perspective
	Function Basics
	Functional Literals in C#
	Storing Functions in C#
	Functional Literals in F#
	Composition
	Functional-Related Language Features
Chapter 3: Builder
	Scenario
	Simple Builder
	Fluent Builder
	Static Initialization
	Communicating Intent
	Nested Builder and Immutability
	Composite Builder
	Builder Marker Interfaces
	Stepwise Builder (Wizard)
	Builder Parameter
	Builder Extension with Recursive Generics
	Lazy Functional Builder
	Builder-Decorator
	Scoping Builder Method
	DSL Construction in F#
	Summary
Chapter 4: Factories
	Scenario
	Factory Method
	Asynchronous Factory Method
	Factory
	Inner Factory
		Physical Separation
	Abstract Factory
	Delegate Factories in IoC
	Object Tracking and Bulk Replacements
		Object Tracking
		Bulk Modifications
	Functional Factory
	Summary
Chapter 5: Prototype
	Deep vs. Shallow Copying
	ICloneable Is Bad
	Deep Copying via Copy Construction
	Note on Record Classes
	Deep Copying with a Special Interface
		Deep Copying and Inheritance
	Deep Copying Guidelines
		Trivially Copyable Types
		Arrays
		Common Collection Types
		MemberwiseClone Is Not Terrible
	Summary
	Serialization
	Prototype Factory
	Source Generators
	Summary
Chapter 6: Singleton
	Singleton by Convention
	Classic Implementation
		Lazy Loading and Thread Safety
		Reusable Base Class
	The Trouble with Singleton
	Per-Thread Singleton
	Ambient Context
		Uses in the .NET Framework
	Singletons and Inversion of Control
	Monostate
	Multiton
	Summary
Chapter 7: Adapter
	Scenario
	Adapter
	Adapter Temporaries
	The Problem with Hashing
	Property Adapter (Surrogate)
	Generic Value Adapter
	Adapter in Dependency Injection
	Bidirectional Adapter
	Adapters in the .NET Framework
	Summary
Chapter 8: Bridge
	Conventional Bridge
	Dynamic Prototyping Bridge
	Summary
Chapter 9: Composite
	Grouping Graphic Objects
	Neural Networks
	Shrink Wrapping the Composite
	Composite Specification
	Summary
Chapter 10: Decorator
	The Basics of Delegation
	Points and Lines
	Adapter-Decorator
	Simulating Multiple Inheritance
	Multiple Inheritance with Interfaces
	Multiple Inheritance with Default Interface Members
	Dynamic Decorator Composition
	Decorator Cycle Policies
	Static Decorator Composition
	Functional Decorator
	Summary
Chapter 11: Façade
	Magic Squares
	Building a Trading Terminal
	An Advanced Terminal
	Where’s the Façade?
	IoC Modules
	Summary
Chapter 12: Flyweight
	User Names
	Text Formatting
	Using Flyweights for Interop
	Summary
Chapter 13: Proxy
	Protection Proxy
	Property Proxy
	Composite Proxy: SoA/AoS
	Composite Proxy with Array-Backed Properties
	Virtual Proxy
	Communication Proxy
	Dynamic Proxy for Logging
	Composite Proxy
	Summary
Chapter 14: Value Object
	Two-Dimensional Point
	Percentage Value
	Units of Measure
	Summary
Chapter 15: Chain of Responsibility
	Scenario
	Method Chain
	Broker Chain
	Functional Chain of Responsibility
	Summary
Chapter 16: Command
	Scenario
	Implementing the Command Pattern
	Undo Operations
	Composite Commands (aka Macros)
	Functional Command
	Queries and Command-Query Separation
	Summary
Chapter 17: Interpreter
	Integer Parsing
	Numeric Expression Evaluator
		Lexing
		Parsing
		Using Lexer and Parser
	Interpretation in the Functional Paradigm
	Transpiler
	Summary
Chapter 18: Iterator
	Array-Backed Properties
	Let’s Make an Iterator
	Improved Iteration
	Iterator Specifics
	Iterator Adapter
	Composite Iteration
	Summary
Chapter 19: Mediator
	Chat Room
	Mediator with Events
	Introduction to MediatR
	Service Bus as Mediator
	Summary
Chapter 20: Memento
	Bank Account
	Undo and Redo
	Memento and Command
	Summary
Chapter 21: Null Object
	Scenario
	Intrusive Approaches
		Nullable Virtual Proxy
	Null Object
	Null Object Singleton
	Dynamic Null Object
		Drawbacks
	Summary
Chapter 22: Observer
	Events
	Weak Event Pattern
	Event Streams
	Property Observers
		Basic Change Notification
		Bidirectional Bindings
		Property Dependencies
		Views
		Case Study: Quadratic Equation Solver
		Circular Recalculation Limitations
	Observable Collections
		Observable LINQ
	Declarative Subscriptions in Autofac
	Summary
Chapter 23: State
	State-Driven State Transitions
	Enum-Based State Machine
	Switch-Based State Machine
	Encoding Transitions with Switch Expressions
	State Machines with Stateless
		Types, Actions, and Ignoring Transitions
		Reentrancy Again
		Hierarchical States
		More Features
	Concurrent State Machines
	Implicit State Machines
	Summary
Chapter 24: Strategy
	Dynamic Strategy
	Static Strategy
	Equality and Comparison Strategies
	Functional Strategy
	Declarative Strategies
	Summary
Chapter 25: Template Method
	Game Simulation
	Template Method Mixin
	Functional Template Method
	Summary
Chapter 26: Visitor
	Intrusive Visitor
	Reflective Visitor
		Extension Methods?
		Functional Reflective Visitor (C#)
		Functional Reflective Visitor (F#)
		Improvements
	What Is Dispatch?
	Dynamic Visitor
	Classic Visitor
		Abstract Classes and Virtual Methods
		Reducing Boilerplate
		Implementing an Additional Visitor
	Type Checks Are Unavoidable
	Acyclic Visitor
	Visitable Null Object
	Visitor Adapter
	Reductions and Transforms
	Functional Visitor in F#
	Summary
Index