lock _log_lock();
#define LOG_NONMEMBER _log_prefix(locked_ostream{std::cerr, _log_lock()}, __FILE__, __func__)
#define LOG _log_member(LOG_NONMEMBER, (const void *)this)
lock _log_lock();
#define LOG_NONMEMBER _log_prefix(locked_ostream{std::cerr, _log_lock()}, __FILE__, __func__)
#define LOG _log_member(LOG_NONMEMBER, (const void *)this)