C++风格的回调对象方法. 采用template实现

今天看了一篇文章，收藏一下代码。读一读很有激情

#include <iostream>
#include <string>
#include <vector>
using namespace std;
template < class Class, typename ReturnType, typename Parameter >
class SingularCallBack
{

public:

    typedef ReturnType (Class::*Method)(Parameter);

    SingularCallBack(Class* _class_instance, Method _method)
    {
        //取得对象实例地址,及调用方法地址
        class_instance = _class_instance;
        method        = _method;
    };

    ReturnType operator()(Parameter parameter)
    {
        // 调用对象方法
        return (class_instance->*method)(parameter);
    };

    ReturnType execute(Parameter parameter)
    {
        // 调用对象方法
        return operator()(parameter);
    };

private:

    Class*  class_instance;
    Method  method;

};

class AClass
{
public:

    AClass(unsigned int _id): id(_id){};
    ~AClass(){};

    bool AMethod(std::string str)
    {
        std::cout << "AClass[" << id << "]: " << str << std::endl;
        return true;
    };

private:

    unsigned int id;

};

typedef SingularCallBack < AClass, bool, std::string > ACallBack;

int main()
{

    std::vector < ACallBack > callback_list;

    AClass a1();
    AClass a2();
    AClass a3();

    callback_list.push_back(ACallBack(&a1, &AClass::AMethod));
    callback_list.push_back(ACallBack(&a2, &AClass::AMethod));
    callback_list.push_back(ACallBack(&a3, &AClass::AMethod));

    for (unsigned int i = ; i < callback_list.size(); i++)
    {
        bool b=callback_list[i]("abc");
    }

    for (unsigned int i = ; i < callback_list.size(); i++)
    {
        callback_list[i].execute("abc");
    }
    cin.get();
    return true;

}