I would disagree with regards to the Person chain. Mainly because being an employee is a role, as opposed to being a kind of people.
It's hard to evaluate whether or not those examples make sense without some pseudocode showing how the classes are used.
Re:Inheritance Is Terrible
by thomasahle on Saturday March 19, 2016 @05:55PM
(#11320660)
Would you also support Shape > Rectangle > Square?
Or are all your super classes abstract?
Re:Inheritance Is Terrible
by Bluestrike2 on Saturday March 19, 2016 @08:21PM
(#11321175)
If we're being cheeky, a square is also a rectangle. Unless I'm misreading your post, I'd expect your superclasses to be as abstract as they needs to be and no more:
Vehicle < Car, Truck, etc.
Person < Employee, Customer, etc.
PhilosophicalBeing < Person < Employee, Customer, etc.A mutable square is not a mutable rectangle, because a mutablr rectangle can change its width independently of its length. This is the classic problem of contravariance: subtyping in the face of mutability.
Re:Inheritance Is Terrible
by Bluestrike2 on Sunday March 20, 2016 @01:56AM
(#11321973)
Good point. Without giving it much if any thought, I made an assumption--that the square is immutable--that probably wouldn't even be accurate in this context. In fact, it's the usual example used to talk about substitutability. Oops.
Person > Employee > Manager
Shape > Rectangle, Circle
Object > anything
Product > Book, TV
I think these are good examples where inheritance makes lot of sense. There is commonality between things and there is specialization (overrides) or definitions (abstract methods). It's wrong to say that the concept of inheritance is evil. Like pretty much everything, it can be severely abused (very deep hierarchies, multiple on inheritence etc). The classic example of OOP abuse is probably things like MFC library.