label_of()

template<typename T>

str kumi::label_of ( )

inlinenodiscardconstevalnoexcept

Extracts the label from a kumi::concepts::field or returns the parameter.

Note

If the unqualified type of input does not model kumi::concepts::field, returns kumi::unkown.

Template Parameters

T	The type to extract label from.

Returns

The label of the field as a kumi::str.

Helper type

namespace kumi::result
{
  template<typename Ts> struct label_of;
 
  template<typename T> using label_of_t = typename name_of<T>::type;
}

Computes the return type of a call to kumi::label_of

Example:

#include <kumi/kumi.hpp>
#include <iostream>
 
struct my_id : kumi::identifier<my_id>
{
  using kumi::identifier<my_id>::operator=; 
  friend constexpr auto to_str(my_id) { return kumi::str{"Specific label"}; }
};
inline constexpr my_id my_kw{};
 
int main()
{
  using namespace kumi::literals;
 
  auto field = ( "x"_id = 1 ); 
  int standard = { 12 };
  auto custom = (my_kw = 255);
 
  std::cout << field << "\n";
  std::cout << kumi::label_of<decltype(field)>() << "\n";
  
  std::cout << standard << "\n";
  std::cout << kumi::label_of<decltype(standard)>() << "\n";
 
  std::cout << custom << "\n";
  std::cout << kumi::label_of<decltype(custom)>() << "\n";
}