* “As I understand it, OOP is mainly about allowing behavior to be reconfigured at runtime. As the introduction to "Design Patterns" puts it: "Polymorphism simp

* “As I understand it, OOP is mainly about allowing behavior to be reconfigured at runtime. As the introduction to "Design Patterns" puts it: "Polymorphism simplifies the definition of clients, decouples objects from each other and lets them vary their relationships to each other at run-time."”* You're talking about polymorphism, not OOP. While polymorphism also exists in OOP, it is not a concept that is exclusive to it. And polymorphism alone doesn't make OOP.