# The EvWatcher class

(PECL ev >= 0.2.0)

## Introduction

EvWatcher is a base class for all watchers( EvCheck, EvChild etc.). Since EvWatcher 's constructor is abstract, one can't(and don't need to) create EvWatcher objects directly.

## Class synopsis

abstract class EvWatcher {
/* Properties */
public $is_active;
public $data;
public $is_pending;
public $priority;
/* Methods */
abstract public __construct()
public clear(): int
public feed( int `$revents` ): void
public getLoop(): EvLoop
public invoke( int `$revents` ): void
public keepalive( bool `$value` = ?): bool
public setCallback( callable `$callback` ): void
public start(): void
public stop(): void
}

## Properties

is_active
  Readonly. `true` if the watcher is active. `false` otherwise.
data
  User custom data associated with the watcher
is_pending
  Readonly .`true` if the watcher is pending, i.e. it has outstanding events, but its callback has not yet been invoked. `false` otherwise. As long, as a watcher is pending(but not active), one must not change its priority.
priority
  int between `Ev::MINPRI` and `Ev::MAXPRI`. Pending watchers with higher priority will be invoked before watchers with lower priority, but priority will not keep watchers from being executed(except for EvIdle watchers). EvIdle watchers provide functionality to suppress invocation when higher priority events are pending.

## Table of Contents

- EvWatcher::clear — Clear watcher pending status
- EvWatcher::__construct — Abstract constructor of a watcher object
- EvWatcher::feed — Feeds the given revents set into the event loop
- EvWatcher::getLoop — Returns the loop responsible for the watcher
- EvWatcher::invoke — Invokes the watcher callback with the given received events bit mask
- EvWatcher::keepalive — Configures whether to keep the loop from returning
- EvWatcher::setCallback — Sets new callback for the watcher
- EvWatcher::start — Starts the watcher
- EvWatcher::stop — Stops the watcher

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