Use initialize method

#include <iostream>

​

class A

{

public:

    A()

    {

    }

​

    void virtual initialize()

    {

        std::cout << "A" << std::endl;

    }

};

​

class B : public A

{

public:

    B() : A()

    {

    }

​

    void virtual initialize() override

    {

        std::cout << "B" << std::endl;

    }

};

​

​

using namespace std;

​

int main()

{

    std::cout << 1 << std::endl;

    A a;

    a.initialize();

    std::cout << 2 << std::endl;

    B b;

    b.initialize();

    std::cout << 3 << std::endl;

    return 0;

}