覆盖虚函数的C ++ baseClass ::方法

Question

If I have the following override of a virtual event:

void derivedClass::method(event)
{

   // my stuff

   baseClass::method(event); // <--

}

what does the // <--- line does? What does it call? I don't think it calls the base class' method because it's virtual (so no body)

Answer 1

As you are suggesting, it calls the base class' method. The fact that it is virtual it only means it can be overridden and still access to the derived class' method from a pointer/reference to the base class.

The reason to do that can be easily seen with an example:

class Base {
public:
    virtual void foo() {
        /* do some generic stuff */
    }
};

class Derived : public Base {
public:
    void foo() {
        /* do some specific stuff */

        /* if you also want to do the generic stuff,
           you can call the same method from the base class. */
        Base::foo();
    }
}

It might be the case that you do not want to do the generic stuff for Derived class. Then you would just remove the call to Base::foo() .

Here you have a good reference on virtual methods .

Answer 2

It does call the base class method. Yes, the derived method is being called "polymorphically", but it can call its base method using Base::method

Answer 3

When qualified name ( <class name>::<method name> ) is used in a class method call, the method is called directly, non-virtually . In your example, baseClass::method is called. Since qualified name is used, the fact that the method is virtual means absolutely nothing and makes no difference whatsoever.