std :: tuple作为类成员

Question

How to create an object with member of type std::tuple ?

I tried to compile this code.

  6 template <class ... T>
  7 class Iterator
  8 {
  9 public:
 10         Iterator(T ... args)
 11                 : tuple_(std::make_tuple(args))
 12         {
 13         }
 14 
 15 private:
 16         std::tuple<T ...> tuple_;
 17 };

But it is unable to compile with the following error.

variadic.cpp: In constructor ‘Iterator<T>::Iterator(T ...)’:
variadic.cpp:11:33: error: parameter packs not expanded with ‘...’:
variadic.cpp:11:33: note:         ‘args’

What is wrong with the code?

Answer 1

args is variadic, so you have to expand it with ... :

: tuple_(std::make_tuple(args...))
//                           ^^^

And you don't need make_tuple for this:

: tuple_(args...)