field_value_of()

template<typename T>

decltype(auto) kumi::field_value_of ( T && t )

inlinenodiscardconstexprnoexcept

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

Note

If the unqualified type of input does not model kumi::concepts::field, simply forwards the parameter

Template Parameters

T	The type to extract the value from<.

Parameters

t	A forwarding reference to the input object.

Returns

A forwarded value of the unwrapped object.

Helper type

namespace kumi::result
{
  template<typename Ts> struct field_value_of;
 
  template<typename T> using field_value_of_t = typename field_value_of<T>::type;
}

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

Example:

#include <kumi/kumi.hpp>
#include <iostream>
 
int main()
{
  using namespace kumi::literals;
 
  auto field = ( "x"_id = 1 ); 
  int standard = { 12 };
 
  std::cout << field << "\n";
  std::cout << kumi::field_value_of(field) << "\n";
  
  std::cout << standard << "\n";
  std::cout << kumi::field_value_of(standard) << "\n";
}