Summary

In this chapter, we covered multiple fundamental GoF structural design patterns. They help us extend our systems from the outside, without modifying the actual classes, leading to a higher degree of cohesion by composing our object graph dynamically.

We started with the Decorator pattern, which extends other objects, at runtime, by using them internally. Decorators can also be chained, allowing even greater flexibility (decorating other decorators). We also used an open source tool named Scrutor that simplifies the decorator pattern usage by extending the built-in ASP.NET Core dependency injection system.

Then, we covered the Composite pattern, which allows us to create complex and flexible data structures. To make the life of its consumer easier, the composite delegates the navigation responsibility to each component.

After that, we covered the Adapter pattern, which allows us to adapt an object to another interface. This pattern is very helpful when we need to...