Those of you familiar with Java are likely familiar with the keyword final, use to stop a class from being inherited. C++11 adds final.
You could have used private constructors to block inheritance.
Here goes the example from the textbook ...
class NoDerive final {};
class Base {};
class Last final : Base {};
class Bad : NoDerive {};
class Bad2 : Last {};
Functions can be declared as final too. They cannot be overridden.
class Circle : public Shape {
public:
virtual void draw() final { cout<<"Circle::draw()"<<endl; }
};
Since the operator definitions have different signatures,
virtual bool operator==( Base& bs ){. . .}
virtual bool operator==( Derived& dr ){. . .}
... dynamic binding won’t work.
int main()
{
Base *bp1 = new Base(1);
Base *bp2 = new Base(2);
if( *bp1 == *bp2 ) { // uses Base::operator==(..)
cout << "Objects are equal" << endl;
Base *bp3 = new Derived(1);
Base *bp4 = new Derived(2);
if (*bp3 == *bp4) // uses Base::operator==(..) too!
cout << "Objects are equal" << endl;
}
We will see how to deal with this once we look at runtime type identification and dynamic casting.
