#include <functional>
#include <iostream>
 
class base {
public:
    std::function<void()> Do;
    base() :Do(std::bind(&base::Do_impl, this)){}
protected:
    base(std::function<void()> d) :Do(std::move(d)){}
    void Do_impl() const {std::cout << "base";}    
};
class derived : public base{
public:
    derived() :base(std::bind(&derived::Do_impl, this)){}
protected:
    void Do_impl() const {std::cout << "derived";}
};
 
int main() {
    derived d;
    d.Do();
}
 

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