« EvWatcher::keepalive EvWatcher::start » PHP Manual EvWatcher Sets new callback for the watcher EvWatcher::setCallback (PECL ev >= 0.2.0) EvWatcher::setCallback — Sets new callback for the watcher 说明 public EvWatcher::setCallback ( callable $callback ) : void Sets new callback for the watcher 参数 callback See Watcher callbacks . 返回值 没有返回值。