Floating point Constant

floating_point_constant.cpp

#include <iostream>
#include <type_traits>

template <auto *V>
struct floating_point_constant {
    static constexpr auto value = *V;
    
    static_assert(std::is_floating_point_v<decltype(value)>);
    
    using value_type = decltype(value);
    using type = floating_point_constant;
    
    constexpr operator value_type() noexcept { return value; }
    constexpr value_type operator()() const noexcept { return value; }
};

constexpr auto foo = 1.23f;
constexpr auto bar = 4.56;
constexpr auto baz = 789;

int main()
{
    std::cout << floating_point_constant<&foo>::value << std::endl;
    std::cout << floating_point_constant<&bar>::value << std::endl;
    //std::cout << floating_point_constant<&baz>::value << std::endl;
}