Inheritance: The Most Misused Pillar of OOP

Inheritance was introduced to promote reuse. But in modern systems, it is one of the biggest sources of fragility. Used correctly, it models specialization. Used incorrectly, it creates tight coupling, broken abstractions, and subtle bugs. Inheritance is powerful. And dangerous. A Brief Historical Context Inheritance emerged strongly in Smalltalk and later C++ as a way to: Reuse behavior Model taxonomies Represent “is-a” relationships But as systems scaled, developers discovered something: Inheritance couples classes more tightly than composition. The child class is structurally bound to the parent. If the parent changes, everything below it may break. What Inheritance Really Means Inheritance is: A specialization relationship A behavioral extension mechanism A polymorphic substitution mechanism Inheritance is not: A code reuse shortcut A way to share utilities A dumping ground for common methods If your only goal is reuse, inheritance is often the wrong tool. ❌ The Wrong Way: Inherita