"是否可以约束自定义点对象？"

Question

我正在尝试使用概念（ serializable<\/code> serialize<\/code> ：

    #include <vector>
    
    // The concept
    template <class T>
    concept serializable = requires (T const& t) 
    { 
        serialize (t); 
    };
    
    namespace detail
    {
        // For ints
        auto serialize (int) { return 1; }
    
        // For std::vector of serializable type
        template <class T>
        requires serializable <T>
        auto serialize (std::vector <T> const&)
        {
            return 2;
        }
    
        // The niebloid
        struct serialize_fn
        {
            template <class T> 
            constexpr auto operator() (T&& t) const
            {
                return serialize (std::forward <T> (t));
            }
        };
    }
    // The CPO
    constexpr inline auto serialize = detail::serialize_fn {};
    
    int main ()
    {
        serialize (2);
        serialize (std::vector { 1, 2, 3 });
    }