/** 獲取第N個(gè)類(lèi)型
*/
template <typename... Cases>
struct select
{
};
template <typename T, typename... Cases>
struct select<T, Cases...> : public select<Cases...>
{
  using ThisType = T;
  using Base = select<Cases...>;
};

#include <functional>
#include "vs-help.h"

class TupleFunc
{
public:
  TupleFunc() { }

  // 函數(shù)的實(shí)際構(gòu)造過(guò)程
  template <typename Ret, typename... Args, typename ParamsSource>
  void makeFuncAndParams(Ret(*func)(Args...), ParamsSource& paramSource)
  {
    makeFuncAndParamsImpl<0>(func, select<Args...>(), paramSource);
  }

  // 實(shí)際調(diào)用
  void invoke() 
  {
    m_func();
  }

private:
  // 實(shí)際調(diào)用初始化
  template <size_t idx, typename Func, typename Select, typename ParamsSource, typename... Params>
  void makeFuncAndParamsImpl(Func&& func, Select, ParamsSource& paramSource, Params&&...args)
  {
    typename Select::ThisType param = std::get<idx>(paramSource);
    makeFuncAndParamsImpl<idx + 1>(func, Select::Base(), paramSource, std::forward<Params>(args)..., std::move(param));
  }
    
  // 結(jié)束調(diào)用
  template <size_t idx, typename Func, typename ParamSource, typename... Params>
  void makeFuncAndParamsImpl(Func&& func, select<>, ParamSource& paramSource, Params&&... args)
  {
    m_func = [func, args...]() { func(args...); };
  }
private:
  std::function<void()> m_func;
};

void print(int x, std::string y)
{
  std::cout << "x: " << x << std::endl;
  std::cout << "y: " << y << std::endl;
}
int main()
{
  std::tuple<int, std::string, std::string> p = { 12, "job", "China" };
  TupleFunc func;
  func.makeFuncAndParams(&print, p);
  func.invoke();
  return 0;
}