C++ : Covariant return type without pointer

Question

I create two simple classes by inheritance, and I add a virtual function and the override in the child class.

class P         


        

Answer 1

It is because the derived type would return a derived instance but the caller would be expecting a parent, this is different from when using pointers, in the pointer case the derived pointer can just slide into the space reserved for the parent pointer but the same is not true when talking about actual instances. You also have the problem that the derived method would return a derived instance but a caller using a parent pointer would have no idea about that and thus probably only destroy the parent parts.

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