#include <iostream>


using namespace std;

using PrintFunc = void(*)(std::string);

void Print(std::string s)
{
    cout << s << endl;
}

int main(int argc, char* argv[])
{
    PrintFunc f = Print;

    f("Hello world");

    return 0;
}

#include <iostream>
#include <memory>


using namespace std;

template<typename T>
using deleted_unique_ptr = std::unique_ptr<T, std::function<void(T *)>>;

int main(int argc, char *argv[])
{
    deleted_unique_ptr<FILE> file(fopen("test", "w"),
    [](FILE * f) {
        cout << __PRETTY_FUNCTION__ << endl;
        fclose(f);
    });
    fputs("Hello world", file.get());

    return 0;
}