By the clients, sure. But by the original authors? This design (it's the basic "convert a switch statement to polymorphism" refactoring) turns a ball of mud s

By the clients, sure. But by the original authors? This design (it's the basic "convert a switch statement to polymorphism" refactoring) turns a ball of mud switch statement into several independently comprehensible classes. Operations can be understood, verified and tested apart from the whole evaluation apparatus. No doubt many programmers today massively (perhaps even criminally) overengineer their software, but the fact remains, the example chosen by the author is a really bad one.