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  1. #include <iostream>
  2. #include <tuple>
  3. #include <typeinfo>
  4.  
  5. template <typename T>
  6. struct function_traits;
  7.  
  8. struct void_type { using type = void; };
  9.  
  10. template <typename T_Ret, typename ...T_Args>
  11. struct function_traits<T_Ret(T_Args...)> {
  12.     // Number of arguments.
  13.     enum { arity = sizeof...(T_Args) };
  14.  
  15.     // Argument types.
  16.     template <size_t i>
  17.     struct args {
  18.         using type
  19.             = typename std::conditional<(i < sizeof...(T_Args)),
  20.                                         std::tuple_element<i, std::tuple<T_Args...>>,
  21.                                         void_type>::type::type;
  22.     };
  23. };
  24.  
  25. int main() {
  26. 	using Arg0 = function_traits<int(float)>::args<0>::type;
  27. 	using Arg1 = function_traits<int(float)>::args<1>::type;
  28.  
  29. 	std::cout << typeid(Arg0).name() << std::endl;
  30. 	std::cout << typeid(Arg1).name() << std::endl;
  31. }
  32.  
Success #stdin #stdout 0s 3468KB
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https://ideone.com/yR6B5P
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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