使用C++0x变长参数模板实现元组

最近有空研究了一下C++0x相关的问题，并且在GCC4.6下用变长参数模板实现元组。

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template<typename ... AllTypes>struct MyTuple;template<> struct MyTuple<> {};template<int N, class T>struct ElementType;template<typename Head, typename ... Tail>struct MyTuple<Head,Tail...>{    MyTuple(Head h, Tail... t)        : tail(t...)        , head(h)    {    }    MyTuple(const MyTuple<Head,Tail...>& t)        : tail(t.tail)        , head(t.head)    {    }    MyTuple(MyTuple<Head,Tail...>&& t)        : tail(t.tail)        , head(t.head)    {    }    MyTuple<Tail...> tail;    Head head;    typedef Head HeadType;    typedef MyTuple<Tail...> TailType;};//获取元组指定元素的值template <int k>struct get_class {    template <typename Head, typename ... Tail>    static typename ElementType<k,MyTuple<Head,Tail...> >::type& get(MyTuple<Head,Tail...>& t )    {         return get_class<k-1>::get(t.tail);    }    template <typename Head, typename ... Tail>    static const typename ElementType<k,MyTuple<Head,Tail...> >::type& get(const MyTuple<Head,Tail...>& t )    {         return get_class<k-1>::get(t.tail);    }};template <>struct get_class<0> {    template <typename Head, typename ... Tail>    static typename MyTuple<Head,Tail...>::HeadType& get(MyTuple<Head,Tail...>& t )    {         return t.head;    }    template <typename Head, typename ... Tail>    static const typename MyTuple<Head,Tail...>::HeadType& get(const MyTuple<Head,Tail...>& t )    {         return t.head;    }};//推导元组指定元素的类型template<int N, class T>struct ElementType{private:  typedef typename T::TailType Next;public:  typedef typename ElementType<N-1, Next>::type type;};template<class T>struct ElementType<0, T>{  typedef typename T::HeadType type;};template < int k,typename Head, typename ... Tail>typename ElementType<k,MyTuple<Head,Tail...> >::type& get(MyTuple<Head,Tail...>& t){    return get_class<k>::get(t);}template < int k,typename Head, typename ... Tail>const typename ElementType<k,MyTuple<Head,Tail...> >::type& get(const MyTuple<Head,Tail...>& t){    return get_class<k>::get(t);}

?使用方式：

    MyTuple<double,int,double,int,string,const char*> t(2.1,0,1.11,6666,"helloworld z","world");    cout << get<0>(t) << get<1>(t) << get<2>(t) << get<3>(t) << get<4>(t) << get<5>(t) << std::endl;    get<0>(t) = 100;    get<1>(t) = 10;    get<4>(t) = "gg world";    const MyTuple<int,int,double,int,string> tc(0,0,111.1,5555,"helloworld");    cout << get<0>(tc) << get<1>(tc) << get<2>(tc) << get<3>(tc) << get<4>(tc) << std::endl;    cout << get<1>( MyTuple<double,char>(3.1415926,'c')) << std::endl;

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