how to avoid undefined execution order for the constructors when using std::make_tuple

Question

How can I use std::make_tuple if the execution order of the constructors is important?

For example I guess the execution order of the constructor of class A and the

Answer 1

I believe the only way to manually unroll the definition. Something like the following might work. I welcome attempts to make it nicer though.

#include 
#include 

struct A { A(std::istream& is) {}};
struct B { B(std::istream& is) {}};

template  
class Parser
{ };

template 
class Parser
{
public:
   static std::tuple parse(std::istream& is) {return std::make_tuple(T(is)); }
};

template 
class Parser
{
public:
   static std::tuple parse(std::istream& is) 
   {
      A t(is);
      return std::tuple_cat(std::tuple(std::move(t)),
         Parser::parse(is));
   }
};


int main()
{
   Parser::parse(std::cin);
   return 1;
}