c++ - Is it possible to typedef a parameter pack? -

is possible typedef parameter pack? example

template<class t, class... args> struct {     typedef t type; // typedef it, derived class can use it.                     // how parameter packs?      // option 1:     typedef args arguments;      // option 2:     using arguments = args;      // option 3: can put in tuple, how can untuple pack     typedef tuple<args...> tuple; }; 

i want using above technique implement following

template<int... values> struct integralsequence {     enum { size = sizeof...(values) };      template <unsigned i>     struct @     {         enum { value = typename tuple_element<i,                         tuple<integral_constant<int, values>...>>::type::value              };     }; };  template<unsigned n> struct ascendingsequence {     typedef integralsequence<ascendingsequence<n-1>::values..., n> type;     using values = type::values; // if works };  template<> struct ascendingsequence<1> {     typedef integralsequence<0> type;     using values = type::values; // if works }; 

you can pack them in tuple, or in arbitrary empty class template (i prefer call pack):

template<typename... args> struct pack { };  template<class t, class... args> struct {     using args = pack<args...>; }; 

if given a e.g. in function template , want deduce args..., can this:

template<typename... args, typename a> void f(pack<args...>, a) { /* use args... here */ }  template<typename a> void f(a a) { f(typename a::args(), a); } 

pack being empty convenient in situations that. otherwise you'd need other means pass args without passing tuple contains data (e.g. wrapping yet empty struct).

or, in class template specialization:

template<typename t, typename = typename t::args> struct b_impl;  template<typename t, typename... args> struct b_impl <t, pack<args...> > {     // use args... here };  template<typename t> using b = b_impl<t>; 

i guess these options of deduction , partial specialization @dyp mentioned.

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edit in response edited question. ok, xy problem. if integralsequence need, can use std::make_integer_sequence in c++14 or check my answer question few minutes ago efficient implementation.