c++ - VC++2013 中嵌套可变参数模板结构的别名

Question

对于模板化的嵌套结构，我可以像下面这样定义别名:

template<typename T>struct Struct
{
    Struct(T value){}

    template<typename T1> struct Nested
    {
        Nested(T1 value){}
    };
};
template<typename T, typename T1>using NameT = struct Struct<T>::Nested<T1>;
using Name = NameT<int, double>; // Alias for a certain instance

有人可以给我提示如何为可变参数声明别名吗？

template<typename... T>struct Struct
{
    Struct(T... value){}

    template<typename T1> struct Nested
    {
        Nested(T1 value){}
    };
};
template<typename... T, typename T1>using NameT = struct Struct<T...>::Nested<T1>; // This seems ok
using Name = NameT<int, double>; // error C976: 'Name': too few template arguments

Answer 1

这会起作用:

template<typename T1, typename... T>using NameT = 
   typename Struct<T...>::template Nested<T1>; // This seems ok
   ^^^^^^^^               ^^^^^^^^
using Name = NameT<int, double>;

请注意参数包必须在末尾，因此定义略有改变。

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