There is a lot that is problematic with OO, especially if it is adhered to with dogma. The worst idea and the one I've experienced most issue with, is the `exte

There is a lot that is problematic with OO, especially if it is adhered to with dogma. The worst idea and the one I've experienced most issue with, is the `extends` keyword in Java, and more generally, the concept of inheritance. Inheritance is terribly overused, and tends to lead to code spaghetti and testing nightmares. Hierarchy is a mental trick we pull on ourselves to make sense of the world, but it rarely works out nicely in systems.