#include namespace lt { std::mt19937_64 UUID::s_engine = std::mt19937_64(std::random_device()()); std::uniform_int_distribution UUID::s_distribution = std::uniform_int_distribution {}; UUID::UUID(uint64_t uuid /* = -1 */): m_uuid(uuid == -1 ? s_distribution(s_engine) : uuid) { } } // namespace lt