#include <iostream>
#include <vector>
#include <string>
#include <tuple>
#include <utility>
using namespace std;



   
class defaultValues
   {
   public:
      static std::tuple<bool,int,unsigned int, size_t, double, float, std::string,
      std::wstring > tup;

 
      static decltype(std::get<0>(tup))& getDefault(bool ) { return std::get<0>(tup); }
      static decltype(std::get<1>(tup))& getDefault(int ) { return std::get<1>(tup); }
      static decltype(std::get<2>(tup))& getDefault(decltype(std::get<2>(tup) )) { return std::get<2>(tup); }
      static decltype(std::get<3>(tup))& getDefault(decltype(std::get<3>(tup))) { return std::get<3>(tup); }
      static decltype(std::get<4>(tup))& getDefault(double ) { return std::get<4>(tup); }
      static decltype(std::get<5>(tup))& getDefault(decltype(std::get<5>(tup)) ) { return std::get<5>(tup); }
      static decltype(std::get<6>(tup))& getDefault(decltype(std::get<6>(tup)) &) { return std::get<6>(tup); }
      static decltype(std::get<7>(tup))& getDefault(decltype(std::get<7>(tup)) &) { return std::get<7>(tup); }
  
   };

std::tuple<bool,int,unsigned int, size_t, double, float, std::string,
      std::wstring> defaultValues::tup = std::make_tuple(false,int(0),0,size_t(0), double(0.0),float(0.0),std::string(""),std::wstring(L""));


int main() {
    std::cout<<defaultValues::getDefault(false)<<std::endl;
    // your code goes here
    return 0;
}

Now I have some questions,

1. I feel the code should be compressible using templates. I tried something like

    template<int N> 
    static decltype(std::get<N>(tup))& getDefault(bool ) { return std::get<N>(tup); }

to replace the functions but it did not work.

2. Why can't I use decltype<std::get<0>> instead of bool in the first function. When I do that I get some ambiguity and the compiler complains.

I would appreciate all input I can get.

CodePudding user response：

As long as you do not have duplicate types in your tuple, you can use the type version of get to reduce the code to

class defaultValues
{
public:
  static std::tuple<bool,int,unsigned int, size_t, double, float, std::string,
  std::wstring > tup;

  template <typename T>
  static auto& getDefault(T) { return std::get<T>(tup); }

};