Design Patterns in C#

Design patterns are solutions to real-world problems which we find multiple times in real-world application development. They can be used as per their fitment along with their validation of their pros and cons

Overview

This repository contains comprehensive implementations of various design patterns in C#. Each pattern is implemented with practical examples, detailed explanations, and demonstrates real-world scenarios where these patterns can be effectively applied.

Design patterns are categorized into three main types:

• Creational Patterns: Deal with object creation mechanisms
• Structural Patterns: Deal with object composition and relationships
• Behavioral Patterns: Deal with communication between objects and the assignment of responsibilities

Implemented Patterns

Creational Patterns

Pattern	Description	Use Case Example
Abstract Factory	Creates families of related objects without specifying their concrete classes	Restaurant cuisine system creating meal combinations
Builder	Constructs complex objects step by step	Beverage preparation system with customizable ingredients
Factory	Creates objects without exposing creation logic	Credit card system creating different card types
Factory Method	Creates objects through inheritance, letting subclasses decide which class to instantiate	Document system creating different page types
Prototype	Creates objects by cloning existing instances	Employee system with shallow and deep copying
Singleton	Ensures a class has only one instance with global access	Thread-safe implementation for shared resources

Structural Patterns

Pattern	Description	Use Case Example
Adapter	Allows incompatible interfaces to work together	Employee payroll system integrating with third-party billing
Decorator	Adds behavior to objects dynamically without altering structure	Pizza ordering system with customizable toppings
Facade	Provides simplified interface to complex subsystems	E-commerce order processing system

Behavioral Patterns

Pattern	Description	Use Case Example
Chain of Responsibility	Passes requests along a chain of handlers	Employee leave approval hierarchy
Command	Encapsulates requests as objects	Document editor with menu operations
Observer	Defines one-to-many dependency between objects	Product availability notification system
Strategy	Defines family of algorithms and makes them interchangeable	Travel booking system with different transportation options

Getting Started

Prerequisites

• .NET 6.0 or later
• Visual Studio 2022 or Visual Studio Code
• C# 10.0 or later

Running the Examples

1. Clone the repository:

   git clone <repository-url>
   cd design-patterns-csharp

2. Navigate to any pattern directory:

   cd Command/Command

3. Build and run the project:

   dotnet build
   dotnet run

Project Structure

Each design pattern follows a consistent structure:

PatternName/
├── PatternName/
│   ├── *.cs (Implementation files)
│   ├── Program.cs (Entry point with examples)
│   └── PatternName.csproj
└── ReadMe.md (Detailed explanation)

Pattern Categories Deep Dive

Creational Patterns

Focus on object creation mechanisms, trying to create objects in a manner suitable to the situation. These patterns provide various object creation mechanisms, which increase flexibility and reuse of existing code.

Key Benefits:

• Encapsulate knowledge about which concrete classes the system uses
• Hide how instances of these classes are created and combined
• Provide flexibility in what gets created, who creates it, how it gets created, and when

Structural Patterns

Deal with object composition or in other words how to build bigger objects from smaller ones. These patterns explain how to assemble objects and classes into larger structures while keeping these structures flexible and efficient.

Key Benefits:

• Help ensure that when one part changes, the entire structure doesn't need to change
• Provide different ways to create relationships between objects
• Make it easier to compose interfaces and implementations

Behavioral Patterns

Focus on communication between objects and the assignment of responsibilities between objects. These patterns are concerned with algorithms and the assignment of responsibilities between objects.

Key Benefits:

• Help define how objects interact and communicate
• Distribute responsibilities between objects
• Describe not just patterns of objects or classes but also the patterns of communication between them

Best Practices

When to Use Design Patterns

• Identify recurring problems in your codebase
• Apply patterns judiciously - don't force patterns where they're not needed
• Understand the trade-offs - patterns add complexity but provide flexibility
• Consider maintenance - patterns should make code easier to maintain, not harder

Implementation Guidelines

• Start simple - implement the basic pattern first, then add complexity
• Document your intent - make it clear why you chose a particular pattern
• Test thoroughly - patterns often involve multiple classes working together
• Refactor gradually - introduce patterns through refactoring existing code

Learning Path

Beginner Level

1. Singleton - Understand instance control
2. Factory - Learn basic object creation
3. Observer - Grasp event-driven programming

Intermediate Level

4. Strategy - Master algorithm selection
5. Decorator - Understand object enhancement
6. Adapter - Learn interface compatibility

Advanced Level

7. Abstract Factory - Handle complex object families
8. Builder - Master complex object construction
9. Chain of Responsibility - Understand request processing
10. Command - Learn request encapsulation
11. Facade - Simplify complex systems
12. Factory Method - Advanced object creation
13. Prototype - Master object cloning

Contributing

Contributions are welcome! Please feel free to submit a Pull Request. For major changes, please open an issue first to discuss what you would like to change.

Contribution Guidelines

• Follow the existing code style and structure
• Include comprehensive documentation
• Add practical examples
• Update README files accordingly
• Ensure all tests pass

Resources

Books

• "Design Patterns: Elements of Reusable Object-Oriented Software" by Gang of Four
• "Head First Design Patterns" by Eric Freeman
• "Clean Code" by Robert C. Martin

Online Resources

• Refactoring Guru - Design Patterns
• Microsoft .NET Design Patterns
• C# Design Patterns

License

This project is licensed under the MIT License - see the LICENSE file for details.

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Note: Each pattern directory contains its own detailed README with implementation specifics, usage examples, and benefits. Navigate to individual pattern folders for in-depth explanations and code walkthroughs.