#include <boost/function.hpp>

为atoi取别名fun，fun实质上是函数指针

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

void main()
{
    boost::function<int(char *)>fun = atoi;//为atoi取别名fun，fun实质上是函数指针

    std::cout << fun("123") + fun("234") << std::endl;

    fun = strlen;

    std::cout << fun("123") + fun("234") << std::endl;
}

结合boost::bind使用

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

void main()
{
    boost::function<int(char *)>fun;

    fun = boost::bind(strcmp, "ABC", _1);//绑定strcmp，判断和"ABC"是否相同

    std::cout << fun("123") << std::endl;

    std::cout << fun("ABC") << std::endl;
}

function和bind配合使用可以很方便的实现类成员回调，极好的应用于一些需要回调的场合。

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

class manager
{
public:
    void allstart()
    {
        for (int i = 0; i < 10; i++)
        {
            if (workid)
            {
                workid(i);
            }
        }
    }
    void setcallback(boost::function<void(int)>newid)//绑定调用
    {
        workid = newid;
    }
public:
    boost::function<void(int)> workid;
};

class worker
{
public:
    void run(int toid)
    {
        id = toid;
        std::cout << id << "工作" << std::endl;
    }
public:
    int id;
};

void main()
{
    manager m;
    worker w;

    m.setcallback(boost::bind(&worker::run, &w, _1));//绑定
    //类的成员函数需要对象来调用，绑定了一个默认的对象

    m.allstart();
}

ref库

当在某些情况下需要拷贝对象参数时，如果该对象无法进行拷贝，或者拷贝代价过高，这时候就可以选择ref

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

void print(std::ostream &os, int i)
{
    os << i << std::endl;
}

void main()
{
    boost::function<void(int)>pt = boost::bind(print, boost::ref(std::cout), _1);//std::cout不能拷贝，所以用ref

    std::vector<int>v;
    v.push_back(11);
    v.push_back(12);
    v.push_back(13);

    for_each(v.begin(), v.end(), pt);
}