Introduction to OOP Chapter 16: Overriding : next previous audio real text

A Safe Variance Change

C++ allows the following type of change in signature: 
class Parent {
public:
	Parent * clone () { return new Parent(); }
};

class Child : public Parent {
public:
	Child * clone () { return new Child(); }
};
No type errors can result from this change.
Intro OOP, Chapter 16, Slide 24