Design Patterns in C++: A Modern Approach to Creating Flexible Code

The book "Design Patterns in C++" is a practical guide to applying the 23 classic GoF (Gang of Four) patterns in modern C++. The material is aimed at developers who already have a grasp of the language basics (classes, inheritance, polymorphism, templates) and want to elevate their code quality to a professional level.

The author systematically breaks down three groups of patterns:

• Creational (Singleton, Factory Method, Abstract Factory, Builder, Prototype) — managing the object creation process;
• Structural (Adapter, Bridge, Composite, Decorator, Facade, Flyweight, Proxy) — organizing relationships between classes;
• Behavioral (Chain of Responsibility, Command, Interpreter, Iterator, Mediator, Memento, Observer, State, Strategy, Template Method, Visitor) — distributing responsibilities and algorithms.

Each pattern is examined using a consistent framework:

• the motivation and problem the pattern solves;
• UML class diagram;
• implementation in C++17/20 using modern features (auto, smart pointers, lambdas, optional, variant);
• a real-world example (game engine, GUI framework, network server);
• comparison with alternatives and antipatterns.

Special attention is given to:

• safe memory management (RAII, std::unique_ptr, std::shared_ptr);
• multithreading and patterns in a concurrent environment;
• composition over inheritance;
• integrating patterns into an existing codebase.

The book will be useful for:

• junior developers who want to advance to the middle level;
• middle developers seeking to systematize their knowledge;
• team leads and architects choosing approaches for complex projects;
• senior students in technical fields.

After reading, you will learn how to:

• recognize typical architectural problems and choose the appropriate pattern;
• write code that is easy to extend without modifying existing classes (the Open/Closed principle);
• reduce module coupling and increase reusability;
• skillfully combine multiple patterns in a single project;
• avoid common implementation mistakes (e.g., the "singleton antipattern" or "god object").

All examples are available in a GitHub repository and have been tested under GCC, Clang, and MSVC. The book is written in a lively style, with a focus on practice — minimal theory, maximum working code.