#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("") + fun("") << std::endl;

     fun = strlen;

     std::cout << fun("") + fun("") << 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("") << 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 = ; i < ; 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();
     v.push_back();
     v.push_back();

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