The Only Time You Should Use Polymorphism

The only time you should use subtype polymorphism is when you have behavioural variation in the subtypes. I teach two university courses on object oriented programming and I see this problem a lot. Let me explain. 💚 BUY MY BOOK: leanpub.com/the-object-oriented-way/ RECOMMENDED READING: 🛠️ geni.us/k8KhT3 (Refactoring) ⭐️ geni.us/zzlx (Dependency Injection: Principles, Practices, and Patterns) 💎 geni.us/hNDE (Elegant Objects) 🏛️ geni.us/IBhtLnh (Clean Architecture) 🧩 geni.us/nlbA6 (Head First: Design Patterns) Read my FREE book on Object Oriented Programming: 🚀 theobjectorientedway.com/ Watch next:    • Always Use Interfaces   CONTENTS: 00:00 Thesis 01:16 Example 1 03:28 Example 2 06:25 Example 3 13:26 S