Design Patterns Documentation

This repository contains a comprehensive guide to the 23 Gang of Four (GoF) design patterns implemented in C++.

📚 What's Included

• Complete documentation of all 23 design patterns
• Real-world analogies for easy understanding
• Modern C++ implementations using C++11/14/17 features
• Practical examples with usage demonstrations
• Bad usage examples to show common mistakes

🗂️ Pattern Categories

🏗️ Creational Patterns (5)

Focus on object creation mechanisms:

• Singleton
• Factory Method
• Abstract Factory
• Builder
• Prototype

🧱 Structural Patterns (7)

Focus on object composition and relationships:

• Adapter
• Bridge
• Composite
• Decorator
• Facade
• Flyweight
• Proxy

🔄 Behavioral Patterns (11)

Focus on communication between objects:

• Chain of Responsibility
• Command
• Interpreter
• Iterator
• Mediator
• Memento
• Observer
• State
• Strategy
• Template Method
• Visitor

📖 How to Use

1. Read the Documentation: Open design_patterns.md to explore all patterns
2. Compile Examples: Each pattern includes complete, compilable C++ code
3. Learn by Example: Study the real-world analogies and implementations

🔧 Compilation Instructions

All code examples are written in modern C++ and can be compiled with:

# For individual pattern examples
g++ -std=c++17 -Wall -Wextra -o pattern_example pattern_code.cpp

# Example for Singleton pattern
g++ -std=c++17 -Wall -Wextra -o singleton singleton.cpp

Requirements

• C++11 or later compiler (GCC, Clang, MSVC)
• Standard library support

🎯 Learning Path

Beginner

Start with these fundamental patterns:

1. Singleton - Learn about controlled instantiation
2. Factory Method - Understand object creation abstraction
3. Observer - Grasp event-driven programming
4. Strategy - See algorithm encapsulation

Intermediate

Progress to these structural patterns:

1. Adapter - Interface compatibility
2. Decorator - Dynamic behavior addition
3. Facade - Simplifying complex systems
4. Composite - Tree structures

Advanced

Master these complex behavioral patterns:

1. Command - Request encapsulation
2. State - Behavior based on state
3. Visitor - Operations on object structures
4. Mediator - Object interaction management

💡 Key Benefits

• Reusability: Proven solutions to common problems
• Maintainability: Well-structured, modular code
• Communication: Common vocabulary for developers
• Best Practices: Industry-standard approaches

🔍 Pattern Selection Guide

Problem	Recommended Pattern
Need only one instance	Singleton
Create objects without specifying types	Factory Method
Add behavior without changing classes	Decorator
Simplify complex interfaces	Facade
Notify multiple objects of changes	Observer
Encapsulate algorithms	Strategy
Handle requests in chain	Chain of Responsibility
Undo operations	Command + Memento

📝 Code Quality Features

• Modern C++: Uses smart pointers, RAII, and move semantics
• Thread Safety: Includes thread-safe implementations where relevant
• Exception Safety: Proper error handling and resource management
• const Correctness: Appropriate use of const qualifiers
• SOLID Principles: Demonstrates good object-oriented design

🚀 Getting Started

1. Clone or download this repository
2. Open design_patterns.md in your favorite Markdown viewer
3. Copy any pattern's code to test it locally
4. Modify examples to fit your specific use cases

📚 Additional Resources

• Gang of Four Book - Original design patterns reference
• Refactoring Guru - Interactive pattern explanations
• C++ Core Guidelines - Modern C++ best practices

🤝 Contributing

Feel free to:

• Report issues or suggest improvements
• Add more real-world examples
• Contribute additional patterns or variations
• Improve documentation clarity

📄 License

This documentation is provided for educational purposes. Feel free to use and modify the code examples for your projects.

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Happy Coding! 🎉

Remember: Design patterns are tools, not rules. Use them when they solve real problems, not just because you can.