oop-inheritance-composition

Inheritance creates tight hierarchies best for shared behavior and polymorphism; composition uses delegation for flexibility and code reuse. Choose inheritance for true "is-a" relationships and composition for "has-a" relationships to build maintainable, testable systems that adapt to change.

Evaluate whether subclasses represent true specializations (inheritance) or whether behavior can be delegated to contained objects (composition). Apply template method patterns for shared logic in hierarchies, and use mixins or delegation for cross-cutting concerns. Document tradeoffs to ensure extensibility.

Deep inheritance hierarchies create brittle systems where changes to parent classes cascade unpredictably, reduce flexibility, and complicate testing. Composition avoids these constraints by letting you swap implementations at runtime and keep classes loosely coupled.

Yes. Use inheritance for abstract base classes and template methods that define shared contracts, then compose concrete implementations to handle specific behavior. This hybrid approach balances polymorphism benefits with composition's flexibility and testability.

Delegation wraps objects and forwards method calls to composed instances; mixins in Python add behavior through multiple inheritance or composition. Both patterns enable code reuse and system extensibility without rigid class hierarchies, supporting polymorphism through interface contracts.

Decorator, Strategy, and Observer patterns encapsulate behavior in composed objects. Abstract versus concrete implementations define boundaries; hooks in template methods coordinate inheritance and composition. These patterns create maintainable systems where behavior is swappable and testable.