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<html><head><title>Win32::ChangeNotify (Perl in a Nutshell, 2nd Edition)</title><link rel="stylesheet" type="text/css" href="../style/style1.css" /><meta name="DC.Creator" content="Stephen Spainhour" /><meta name="DC.Format" content="text/xml" scheme="MIME" /><meta name="DC.Language" content="en-US" /><meta name="DC.Publisher" content="O'Reilly & Associates, Inc." /><meta name="DC.Source" scheme="ISBN" content="0596002416L" /><meta name="DC.Subject.Keyword" content="stuff" /><meta name="DC.Title" content="Perl in a Nutshell, 2nd Edition" /><meta name="DC.Type" content="Text.Monograph" /></head><body bgcolor="#ffffff"><img src="gifs/smbanner.gif" usemap="#banner-map" border="0" alt="Book Home" /><map name="banner-map"><area shape="rect" coords="1,-2,616,66" href="index.htm" alt="Java and XSLT" /><area shape="rect" coords="629,-11,726,25" href="jobjects/fsearch.htm" alt="Search this book" /></map><div class="navbar"><table width="684" border="0"><tr><td align="left" valign="top" width="228"><a href="ch22_02.htm"><img src="../gifs/txtpreva.gif" alt="Previous" border="0" /></a></td><td align="center" valign="top" width="228" /><td align="right" valign="top" width="228"><a href="ch22_04.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr></table></div><h2 class="sect1">22.3. Win32::ChangeNotify</h2><p><a name="INDEX-3211" /><a name="INDEX-3212" />This module provides access to Win32change-notification objects, letting you monitor events relating tofiles and directory trees. The constructor for this class is<tt class="literal">new</tt>, which creates a ChangeNotify object for aspecified path and indicates how it should be monitored:</p><blockquote><pre class="code">$ntfy = Win32::ChangeNotify->new(<em class="replaceable"><tt>path</em>, <em class="replaceable">subtree</em>, <em class="replaceable">events</tt></em>);$ntfy->wait or warn "Something has failed: $!");</pre></blockquote><p>The function returns a reference to the object as<tt class="literal">$ntfy</tt>. <em class="replaceable"><tt>path</tt></em> is thepathname of the directory to monitor.<em class="replaceable"><tt>subtree</tt></em> is a Boolean value that, if true,forces the object to monitor all subdirectories of theobject's path. The <em class="replaceable"><tt>events</tt></em>parameter indicates the type of events that will trigger anotification. It can be one of the following string values:</p><a name="ch22-35-fm2xml" /><table border="1" cellpadding="3"><tr><th><p>Value</p></th><th><p>Description</p></th></tr><tr><td><p>ATTRIBUTES</p></td><td><p>Any attribute change</p></td></tr><tr><td><p>DIR_NAME</p></td><td><p>Any directory name change</p></td></tr><tr><td><p>FILE_NAME</p></td><td><p>Any filename change (creating/deleting/renaming)</p></td></tr><tr><td><p>LAST_WRITE</p></td><td><p>Any change to a file's last write time</p></td></tr><tr><td><p>SECURITY</p></td><td><p>Any security descriptor change</p></td></tr><tr><td><p>SIZE</p></td><td><p>Any change in a file's size</p></td></tr></table><p><p>The following methods are used on notification objects created by<tt class="literal">new</tt>.</p><a name="INDEX-3213" /><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>close</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>$<em class="replaceable">ntfy</em>->close( )</pre><p><a name="INDEX-3213" />Stops the monitoring done by thenotification object and destroys the object. This happensautomatically when the program exits.</p></div><a name="INDEX-3214" /><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>reset</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>$<em class="replaceable">ntfy</em>->reset( )</pre><p><a name="INDEX-3214" />Resets the object to begin monitoringagain after a change has occurred.</p></div><a name="INDEX-3215" /><a name="INDEX-3216" /><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>wait</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>$<em class="replaceable">ntfy</em>->wait([<em class="replaceable">timeout</em>])</pre><p><a name="INDEX-3215" />The <tt class="literal">wait</tt> method isinherited from the Win32::IPC package. It waits for the notificationobject to signal when it detects a change.<em class="replaceable"><tt>timeout</tt></em> is the maximum time to wait (inmilliseconds). If <em class="replaceable"><tt>timeout</tt></em> is omitted, themethod waits forever. If <em class="replaceable"><tt>timeout</tt></em> is<tt class="literal">0</tt>, the function returns immediately. The functionreturns the following values:</p><dl><dt><b><tt class="literal">+1</tt></b></dt><dd>The object is signaled.</p></dd><dt><b><tt class="literal">0</tt></b></dt><dd>Timed out.</p></dd><dt><b><tt class="literal">undef</tt></b></dt><dd>An error occurred.</p></dd></dl><p>Use <tt class="literal">reset</tt> on the object after<tt class="literal">wait</tt> if you wish to continue monitoring.<a name="INDEX-3216" /></p></div><hr width="684" align="left" /><div class="navbar"><table width="684" border="0"><tr><td align="left" valign="top" width="228"><a href="ch22_02.htm"><img src="../gifs/txtpreva.gif" alt="Previous" border="0" /></a></td><td align="center" valign="top" width="228"><a href="index.htm"><img src="../gifs/txthome.gif" alt="Home" border="0" /></a></td><td align="right" valign="top" width="228"><a href="ch22_04.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr><tr><td align="left" valign="top" width="228">22.2. Win32::Console</td><td align="center" valign="top" width="228"><a href="index/index.htm"><img src="../gifs/index.gif" alt="Book Index" border="0" /></a></td><td align="right" valign="top" width="228">22.4. Win32::Eventlog</td></tr></table></div><hr width="684" align="left" /><img src="../gifs/navbar.gif" usemap="#library-map" border="0" alt="Library Navigation Links" /><p><p><font size="-1"><a href="copyrght.htm">Copyright © 2002</a> O'Reilly & Associates. 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