#include <iostream>
#include <functional>

using namespace std;

struct FirstClass
{
    FirstClass(): x(0)
    {
    }

    int get_x() const
    {
        return x;
    }

    function<int ()> f1 = [this]() -> int
    {
        cout << "called member function f1..." << endl;
        ++x;
        f1 = f2;
        return 5;
    };

private:

    function<int ()> f2 = [this]() -> int
    {
        cout << "called member function f2..." << endl;
        return x;
    };

    int x;
};

int main()
{
    FirstClass m;
    m.f1();
    m.f1();

    function<int ()> f3 = []() -> int
    {
        cout << "called free function f3..." << endl;
        return 100500;
    };

    m.f1 = f3;
    m.f1();

    return 0;
}