boost :: function和boost :: bind如何工作

#include<iostream>
#include<boost/function.hpp>
#include<boost/bind.hpp>

void foo(int n) {
    std::cout << "foo: " << n << std::endl;
}

struct Bar {
    void operator()(int n) {
        std::cout << "Bar::operator(): " << n << std::endl;
    }
};

int main() {
    boost::function<void(int)> f;

    f = &foo;
    f(1);

    f = Bar();
    f(2);

    return 0;
}

#include<iostream>
#include<boost/bind.hpp>
#include<boost/function.hpp>

void foo(int a, int b) {
    std::cout << "foo: " << a << ", " << b << std::endl;
}

int main() {
    boost::function<void()> f;

    f = boost::bind(&foo, 1, 2);
    f();

    return 0;
}