Favor Composition over Inheritance

Have you ever tried to reuse behavior by subclassing a class… only to find yourself tangled in override hell?

Or added a new feature by extending a base class, and suddenly inherited methods you didn’t need, or worse, didn’t understand?

If yes, you’ve likely felt the pain of misusing inheritance, and missed out on a more flexible alternative: composition.

In this chapter, we’ll explore what “Favor Composition Over Inheritance” really means, why it matters, and how to apply it in real-world systems.

Favor assembling behavior using smaller components (composition) instead of relying on rigid class hierarchies (inheritance).

Inheritance models an is-a relationship.Composition models a has-a relationship.

When you use composition, you build objects by combining smaller pieces of behavior.When you use inheritance, you build objects by extending or modifying existing classes.

Key idea: Inheritance reuses structure. Composition reuses behavior.