Variadic Template（七）

 

使用组合的方式实现tuple的功能

#include<iostream>
using namespace std;

template<typename... Values> class tup;
template<> class tup<>{};


// to realize function of tuple by using compistion
template<typename Head, typename... Tail>
class tup<Head, Tail...>
{
    typedef tup<Tail...> composited;
protected:
    composited m_tail;
    Head m_head;
public:
    tup(){};
    tup(Head v, Tail... vtail)
        :m_tail(vtail...), m_head(v){}
    
    Head head(){
        return m_head;
    }

    composited& tail(){
        return m_tail;
    }
};

int main() 
{
    tup<int, float, string>it1(41,6.3,"nico");
    cout << "sizeof(it1) = " << sizeof(it1) << endl;
    cout << "it1.head() = " << it1.head() << endl;
    cout << "it1.tail().head() = " << it1.tail().head() << endl;
    cout << "it1.tail().tail().head() = " << it1.tail().tail().head() << endl;
    return 0; 
}