OOP Best Practices

Overview

Object-oriented programming best practices help teams build maintainable, testable, and extensible code.

Core Practices

• Encapsulate state and behavior together
• Favor composition over inheritance
• Keep classes small and cohesive
• Program to interfaces where useful

classDiagram
    class OrderService
    class PaymentGateway
    class InventoryGateway
    OrderService --> PaymentGateway
    OrderService --> InventoryGateway

Practical Example

A service class should orchestrate domain actions while gateway interfaces isolate external integrations.

Production Example

Large systems commonly use interface-based adapters to replace payment providers without changing core order logic.

Common Pitfalls

• God classes with mixed responsibilities
• Deep inheritance hierarchies that are hard to reason about
• Domain models leaking persistence concerns

Key Takeaways

• OOP works best with cohesive classes and clear boundaries.
• Composition improves flexibility and testability.
• External dependencies should be abstracted at boundaries.