#include <iostream>
#include <functional>

class ClassXY
{
    std::function<void()> function;

public:
    ClassXY(std::function<void()> f)
        : function(f)
    {}

    void call()
    {
        function();  // Calls the function
    }
};

class Handler
{
public:
    void HandleButtonEvent()
    {
        std::cout << "Handler::HandleButtonEvent\n";
    }
};

int main()
{
    Handler* handler = new Handler;

    ClassXY xy(std::bind(&Handler::HandleButtonEvent, handler));

    xy.call();
}