Summary

This chapter delved into DI, understanding its crucial role in crafting adaptable systems. We learned how DI applies the IoC principle, shifting dependency creation from the objects to the composition root. We explored the IoC container’s role in object management, service resolution and injection, and dependency lifetime management. We tackled the Control Freak anti-pattern, advocating for DI over using the new keyword.

We revisited the Strategy pattern and explored how to use it with DI to compose complex object trees. We learned about the principle of composition over inheritance, which encourages us to inject dependencies into the classes instead of relying on base class features and inheritance. We explored different ways of injecting dependencies into objects, including constructor injection, property injection, and method injection.

We learned that a guard clause is a condition that must be met before a method is executed, often used to prevent null dependencies...