fundamentals/oop-design-principles

What problem does it solve?

This Skill ensures object-oriented systems avoid brittle hierarchies, tightly coupled dependencies, and hard-coded variability by codifying the three core principles described in the instructions.

Core Features & Use Cases

• Encapsulate What Varies: Identify volatile logic such as tax calculations, payment gateways, or export formats and move it into dedicated helpers or classes.
• Program to an Interface, Not an Implementation: Replace direct class dependencies with interface contracts so each role relies on abstractions and can accept new collaborators.
• Favor Composition Over Inheritance: Prefer delegating behavior to interchangeable components instead of proliferating subclasses with combinatorial features.
• Use Case: While refactoring a multi-tenant platform, apply these steps to isolate provider differences, define interface layers, and swap inheritance hierarchies with composition strategies.

Quick Start

Review a subsystem, separate the changing logic into dedicated collaborators, and swap direct inheritance with interface-driven composition.