/* these may evaluate ev multiple times, and the other arguments at most once */
/* either use ev_init + ev_TYPE_set, or the ev_TYPE_init macro, below, to first initialise a watcher */
/* these may evaluate ev multiple times, and the other arguments at most once */
/* either use ev_init + ev_TYPE_set, or the ev_TYPE_init macro, below, to first initialise a watcher */