<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<title>Watchers</title>
</head>
<body><div class="manualnavbar" style="text-align: center;">
<div class="prev" style="text-align: left; float: left;"><a href="ev.examples.html">Examples</a></div>
<div class="next" style="text-align: right; float: right;"><a href="ev.watcher-callbacks.html">Watcher callbacks</a></div>
<div class="up"><a href="book.ev.html">Ev</a></div>
<div class="home"><a href="index.html">PHP Manual</a></div>
</div><hr /><div id="ev.watchers" class="chapter">
<h1>Watchers</h1>
<p class="para">
A watcher is an object that gets created to record interest in some event.
For instance, the following code waits for
<strong><code>STDIN</code></strong>
to become readable:
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// Wait until STDIN is readable<br /></span><span style="color: #0000BB">$w </span><span style="color: #007700">= new </span><span style="color: #0000BB">EvIo</span><span style="color: #007700">(</span><span style="color: #0000BB">STDIN</span><span style="color: #007700">, </span><span style="color: #0000BB">Ev</span><span style="color: #007700">::</span><span style="color: #0000BB">READ</span><span style="color: #007700">, function (</span><span style="color: #0000BB">$watcher</span><span style="color: #007700">, </span><span style="color: #0000BB">$revents</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">"STDIN is readable\n"</span><span style="color: #007700">;<br />});<br /></span><span style="color: #0000BB">Ev</span><span style="color: #007700">::</span><span style="color: #0000BB">run</span><span style="color: #007700">(</span><span style="color: #0000BB">Ev</span><span style="color: #007700">::</span><span style="color: #0000BB">RUN_ONCE</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</p>
<p class="para">
All the watcher constructors automatically start the watchers.
<em>createStopped</em>
methods create stopped watchers(e.g.
<span class="methodname"><a href="evio.createstopped.html" class="methodname">EvIo::createStopped()</a></span>
)
</p>
<p class="para">
Note that a watcher will automatically be stopped when the watcher object is
destroyed. Therefore, the watcher objects returned by the constructors or
factory methods should be kept.
</p>
<p class="para">
Note also that all methods changing some watcher property(
<em class="emphasis">set</em>
,
<var class="varname"><var class="varname">priority</var></var>
etc.) automatically stop and start it again if it is active, which means
pending events get lost.
</p>
<p class="para">
See also:
<a href="ev.watcher-callbacks.html" class="link">Watcher callbacks</a>
.
</p>
</div>
<hr /><div class="manualnavbar" style="text-align: center;">
<div class="prev" style="text-align: left; float: left;"><a href="ev.examples.html">Examples</a></div>
<div class="next" style="text-align: right; float: right;"><a href="ev.watcher-callbacks.html">Watcher callbacks</a></div>
<div class="up"><a href="book.ev.html">Ev</a></div>
<div class="home"><a href="index.html">PHP Manual</a></div>
</div></body></html>
