The Structural Design Toolkit for C#

Composition, Delegation, and Collaboration through Six Core Design Patterns

Modern software systems must remain flexible, maintainable, and open to continuous change. While object creation often receives significant attention, the long-term quality of software is largely determined by how objects are structured, composed, and allowed to collaborate. Poor structural decisions can quickly lead to rigid designs that are difficult to extend or refactor. This book focuses on the structural design patterns that remain highly relevant in modern C# and .NET development. Rather than presenting patterns as rigid templates to memorize, it treats them as practical design mechanisms that help developers manage variation, simplify collaboration between components, and build systems that can evolve over time.

Part I of the book explores six essential structural patterns that continue to play an important role in modern software design: Decorator,