boost库学习笔记 代码示例3 boost::bind

/*
 * bind.cpp
 *
 * Created on: 2013-7-16
 * Author: root
 */
#include <vector>
#include <string>
#include <iostream>
#include <map>

#include <boost/bind.hpp>

using namespace std;

class personal_info
{
public:
    std::string name_;
    std::string surname_;
    unsigned int age_;

public:
    personal_info(const string& n,const string& s, unsigned int age):
        name_(n),surname_(s),age_(age) { }

    string name()const { return name_; }

    string surname()const { return surname_; }

    unsigned int age()const { return age_; }
};
//构造输出流
std::ostream& operator<<(std::ostream& os, const personal_info& pi)
{
    os << pi.name_ << ' ' << pi.surname_ << ' ' << pi.age_ << '\n';
    return os;
}

void print_string(const string& s)
{
    cout << s << '\n';
}

//绑定的复制问题
class tracer
{
public:
    tracer(){ cout << "tracer()\n"; }
    tracer(const tracer& other) { cout << "tracer(const tracer& other)\n"; }
    tracer& operator=(const tracer& other) { cout << "tracer& operator=(const tracer& other)\n"; return *this;}
    ~tracer(){ cout << "~tracer()\n"; }

    void print(const string& s)
    {
        cout << s << '\n';
    }
};

/*
int main()
{
//灵活对类结构体根据不成成员排序
    std::vector<personal_info> vec;

    vec.push_back(personal_info("Little","John",30));
    vec.push_back(personal_info("Friar","Tuck",50));
    vec.push_back(personal_info("Robben","Hord",40));
    vec.push_back(personal_info("Jerry","Park",36));
    vec.push_back(personal_info("Smith","Jim",33));

    //按年龄排序
    std::sort(vec.begin(),vec.end(),
            boost::bind(
                    std::less<unsigned int>(),//第一个绑定函数，函数有括号,sort调用的less函数需要返回bool的值类型，但标准库函数都包含
//                    typedef result_type,就不需要显示给出值类型.完整为 boost::bind<bool>(std::less<unsigned int>(),_1,_2)
                    boost::bind(&personal_info::age,_1), //第二个为绑定器，函数无括号，＿1为less的参数
                    boost::bind(&personal_info::age,_2)) );//第三个为绑定器，函数无括号，＿2为less的参数

    std::cout << vec[0] << '\n' <<
            vec[1] << '\n' <<
            vec[2] << '\n' <<
            vec[3] << '\n' <<
            vec[4] << '\n';

    //按后缀名排序
    std::sort(vec.begin(),vec.end(),
            boost::bind(
                    std::less<std::string>(),//第一个绑定函数，函数有括号
                    boost::bind(&personal_info::surname,_1), //第二个为绑定器，函数无括号，＿1为less的参数
                    boost::bind(&personal_info::surname,_2)) );//第三个为绑定器，函数无括号，＿2为less的参数

    std::cout << vec[0] << '\n' <<
            vec[1] << '\n' <<
            vec[2] << '\n' <<
            vec[3] << '\n' <<
            vec[4] << '\n';
//================================================
//    复制问题
    tracer t;
    boost::bind(&tracer::print,t,_1)(std::string("I'm call on a copy of it\n"));
//绑定时使用拷贝对象可以不依赖原对象的生命期，但会影响效率，可以使用使用boost::ref(t),或
    boost::bind(&tracer::print,&t,_1)(std::string("I'm call on direct\n")); //此时bind依赖原对象的生命期

//================================================
    //绑定到成员变量 直接获取得到data而不是key
    std::map<int ,std::string> my_map;
    my_map[0] = "smithy";
    my_map[1] = "jerry";

//    std::for_each(my_map.begin(),my_map.end(),
//            boost::bind(&print_string,boost::bind(&std::map<int ,std::string>::value_type::second,_1)));

    typedef std::map<int ,std::string> map_type;
        std::for_each(my_map.begin(),my_map.end(),
                boost::bind(&print_string,boost::bind(&map_type::value_type::second,_1)));
}
*/