boost库学习笔记 代码示例2 boost::function

/*
 * function2.cpp
 *
 * Created on: 2013-7-24
 * Author: root
 */

#include <iostream>
#include "boost/function.hpp"
#include "boost/bind.hpp"
/*
//带状态的类对象
class keeping_state {
    int total_;
public:
    keeping_state():total_(0){}

    int operator()(int i) { //括号重载 void operator()()
        total_+= i;
        return total_;
    }

    int total() const {
        return total_;
    }
};

int main() {
    keeping_state ks;
//    boost::function<int(int)> f1;
////    f1 = ks; 使用拷贝对象时并不能同时改变total_
//    f1 = boost::ref(ks);//使用引用, 常量引用boost::cref
//
//    boost::function<int(int)> f2;
//    f2 = boost::ref(ks);

    //第二种示例
    boost::function1<int,int> f1;
//    f1 = ks;使用拷贝对象时并不能同时改变total_
    f1 = boost::ref(ks);

    boost::function1<int,int> f2(f1);
    boost::function1<short,short> f3(f2);


    std::cout << "The current f1 total is " << f1(10) << '\n';
    std::cout << "The current f2 total is " << f2(10) << '\n';
    std::cout << "The current f2 total is " << f3(10) << '\n';
    std::cout << "After adding 10 two times,the total is " << ks.total() << '\n';
}
*/


//boost.function 与 boost.bind 合用，让调用代码对被调用代码无所知，实现解耦
class tape_recorder {
public:
    void play() {
        std::cout << "Since my baby left me ...\n";
    }

        void stop() {
        std::cout << "OK, taking a break \n";
    }

        void forward() {
        std::cout << "whizzz\n";
    }

        void rewind() {
        std::cout << "zzzihw\n";
    }

        void record(const std::string& sound) {
        std::cout << "Recorder: "<< sound << " \n";
    }
};

class command {
    boost::function<void()> f_;
public:
    command() {}
    command(boost::function<void()> f):f_(f) { }

    void execute() {
        if(f_) {
            f_();
        }
    }

    template<typename Func> void set_function(Func f) {
        f_ = f;
    }

    bool enabled() const {
        return f_;
    }
};

int main() {
    tape_recorder tr;

    command play(boost::bind(&tape_recorder::play,&tr));
    command stop(boost::bind(&tape_recorder::stop,&tr));
    command forward(boost::bind(&tape_recorder::forward,&tr));
    command rewind(boost::bind(&tape_recorder::rewind,&tr));
    command record;

    //boost::function<void()> f(boost::bind(&tape_recorder::play,&tr));
    //f = boost::ref(play);
    if(play.enabled()){
        play.execute();
    }

    //pass some lyrics
    std::string s="What a beautiful morning...";
    record.set_function(
        boost::bind(&tape_recorder::record,&tr,s));
    record.execute();

}