One of the most damaging things is when they teach inheritance like "a Circle is a Shape, a Rectangle is a Shape, a Square is a Rectangle" kind of thing. The problem is the real world is exceedingly rarely truly hierarchical. Too many people see inheritance as a way to model their domain, and this is doomed to failure.
Where it works is when you invent the hierarchy. Like a GUI toolkit or games. It's hierarchical because you made it hierarchical. In my experience the applications where it really works you can count on one hand, whereas the vast majority of code written is business software for which it doesn't really.
One of the most damaging things is when they teach inheritance like "a Circle is a Shape, a Rectangle is a Shape, a Square is a Rectangle" kind of thing. The problem is the real world is exceedingly rarely truly hierarchical. Too many people see inheritance as a way to model their domain, and this is doomed to failure.
Where it works is when you invent the hierarchy. Like a GUI toolkit or games. It's hierarchical because you made it hierarchical. In my experience the applications where it really works you can count on one hand, whereas the vast majority of code written is business software for which it doesn't really.