front

front_t kumi::front {}

inlineconstexprnodiscard

Callable object used to retrieve the front of a product type.

Note

This function does not take part in overload resolution if t is an empty product type.

Header file

#include <kumi/algorithm/back_front.hpp>

Call Signature

template<product_type T>
[[nodiscard]] constexpr decltype(auto) front(T && t);

Parameters

• t: Product Type to access

Return value

• A reference to the first element of the product type t.

Helper type

    template<kumi::concepts::product_type T> struct front : kumi::stored_member<0, T>
    {
    };
 
    template<kumi::concepts::product_type T> using front_t = typename kumi::result::front<T>::type;
 

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

Examples

Tuple

#include <kumi/kumi.hpp>
#include <iostream>
 
int main()
{
  kumi::tuple x{2.3,18, 5.f};
 
  std::cout << kumi::front(x) << "\n";
  std::cout << kumi::back(x)  << "\n";
 
  kumi::front(x) = 98.5;
  kumi::back(x)  = 66.f;
 
  std::cout << x << "\n";
}

Record

#include <kumi/kumi.hpp>
#include <iostream>
 
int main()
{
  using namespace kumi::literals;
 
  kumi::record x{"a"_id = 2.3,"b"_id = 18, "c"_id = 5.f};
 
  std::cout << kumi::front(x) << "\n";
  std::cout << kumi::back(x)  << "\n";
 
  kumi::front(x) = 98.5;
  kumi::back(x)  = 66.f;
 
  std::cout << x << "\n";
}