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<html><head><title>OLE Automation (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_19.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="ch23_02.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr></table></div><h1 class="chapter">Chapter 23. OLE Automation</h1><div class="htmltoc"><h4 class="tochead">Contents:</h4> <p> <a href="#perlnut2-CHP-23-SECT-1">Creating Objects</a><br /><a href="ch23_02.htm">Automation Methods and Properties</a><br /><a href="ch23_03.htm">Win32::OLE::Enum</a><br /><a href="ch23_04.htm">Win32::OLE::Variant</a><br /><a href="ch23_05.htm">Win32::OLE::Const</a><br /></p></div><p><a name="INDEX-3430" /></a><a name="INDEX-3431" /></a>The Win32::OLE modules give Perlsupport for OLE automation. OLE automation is a Microsoft technologybased on COM that allows objects created by another application to beused and manipulated by a program through a common interface.</p><p><a name="INDEX-3432" /></a>Theapplication (or DLL) that implements the automation interface iscalled the <em class="emphasis">automation server</em>. The applicationthat creates and uses the interface is called the<em class="emphasis">automationcontroller</em><a name="INDEX-3433" /></a> or <em class="emphasis">automationclient</em><a name="INDEX-3434" /></a>. Many popular applications expose theirobjects through automation. Microsoft Word, Excel, and other Officeapplications can be used as automation servers. Automation is widelyused by Active Server Pages (ASP) and CGI scripts to access datarepositories, perhaps via ActiveX Data Objects (ADO). You can evenuse automation to control many development environments and editors.</p><p>To create an <a name="INDEX-3435" /></a>automation object, the server needs to be<em class="emphasis">registered</em> on the system. This is typically doneby the server's installation program, but can bedone manually using a utility such as<em class="emphasis">regsvr32.exe</em>. This involves adding entries tothe system registry to tell COM how to find the component, the typesof interfaces it provides, the type of server it is, etc. You shouldbe able to find the object model, available methods, and propertiesof the interface in the documentation provided by the application.This object model can be used via Perl's objectsyntax to create and control objects in your programs.</p><p><a name="INDEX-3436" /></a>Fourmodules provide automation functionality to Perl:</p><dl><a name="INDEX-3437" /></a><dt><i>Win32::OLE</i></dt><dd>Provides the main interface for OLE automation. You can create oropen automation objects, use their methods, and set their properties.<p></p></dd><a name="INDEX-3438" /></a><dt><i>Win32::OLE::Enum</i></dt><dd>Creates objects for collections and defines an interface forenumerating them.<p></p></dd><a name="INDEX-3439" /></a><dt><i>Win32::OLE::Variant</i></dt><dd>Allows you to convert the Variant data type used in OLE.<p></p></dd><a name="INDEX-3440" /></a><dt><i>Win32::OLE::Const</i></dt><dd>Imports constants from an automation object into your script.<p></p></dd></dl><p>Note that there are a few limitations to Win32::OLE. There iscurrently no support for OCXs or OLE events (notifications generatedby the automation server). Win32::OLE implements the<tt class="literal">IDispatch</tt> interface only, and therefore cannotaccess a custom OLE interface.</p><div class="sect1"><a name="perlnut2-CHP-23-SECT-1" /></a><h2 class="sect1">23.1. Creating Objects</h2><p>Automation objects are represented in Perl as instances of Win32::OLEobjects. The module provides three constructors for creating objectsfrom a registered automation server.</p><a name="INDEX-3441" /></a><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>new</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" true align="left" color="black" /><pre>Win32::OLE->new(<em class="replaceable">progid</em>, [<em class="replaceable">destructor</em>])</pre><p><a name="INDEX-3441" /></a>Creates a new automation object. Thismethod always creates a new instance of the server, even if aprevious instance of the server is running. If the object cannot becreated, <tt class="literal">new</tt> returns <tt class="literal">undef</tt>.</p><p><em class="replaceable"><tt>progid</tt></em>, the program identifier (ProgID),is a string that uniquely identifies an automation object.<em class="replaceable"><tt>progid</tt></em> is used to look up theobject's class ID (CLSID), which is stored in theregistry.</p><p>The second, optional argument to the <tt class="literal">new</tt> methoddescribes a way to destroy the object in case the Perl program diesunexpectedly. <em class="replaceable"><tt>destructor</tt></em> can be either astring with the name of the defined OLE destructor method, or a codereference that will destroy the object. You should use some form of<em class="replaceable"><tt>destructor</tt></em> to close out all your objects,for they can be extremely expensive in terms of system resources. Youcan explicitly destroy an object using the <tt class="literal">undef</tt>function. If you don't explicitly destroy theobject, Perl takes care of it for you when the last reference to theobject goes away.</p><p>Here is what <tt class="literal">new</tt> would look like with thedestructor arguments:</p><blockquote><pre class="code"># Quit is the OLE-defined destructor method$x1 = Win32::OLE->new("Excel.Application", 'Quit');# The object reference is the first argument ($_[0]) passed to new# The code reference will undef it to destroy the object$x2 = Win32::OLE->new("Excel.Application", sub{undef $_[0];})</pre></blockquote><p>Notice that we're supplying Excel.Application as theProgID. Excel supports several different automation objects,including an Application object, WorkBook objects, and several more.You don't necessarily have to create the top-levelobject (Application, in this case) when dealing with automationobjects (this is determined by the automation server). InExcel's case, we could have directly created aWorkSheet object (e.g., Excel.Sheet) or a Chart object, for example.</p></div><a name="INDEX-3442" /></a><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>GetActiveObject</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" true align="left" color="black" /><pre>Win32::OLE->GetActiveObject(<em class="replaceable">progid</em>)</pre><p><a name="INDEX-3442" /></a>Creates anobject for a currently active instance of a server, if one exists. Ifthe server is registered, but no instance of it is running, themethod returns <tt class="literal">undef</tt>. If the server is notregistered, the method will <tt class="literal">croak</tt>.</p><p>You should probably call <tt class="literal">GetActiveObject</tt> inside an<tt class="literal">eval</tt> so that you can do exception handling in theevent that the server is unregistered or is not currently running. Ifthe method returns <tt class="literal">undef</tt>, you can just create anew instance of the server and the object with<tt class="literal">new</tt>.</p></div><a name="INDEX-3443" /></a><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>GetObject</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" true align="left" color="black" /><pre>Win32::OLE->GetObject(<em class="replaceable">filename</em>)</pre><p><a name="INDEX-3443" /></a>Creates an automation objectbased on a document. <em class="replaceable"><tt>filename</tt></em> is the fullpathname of the document, which can be optionally followed byadditional item subcomponents separated by exclamation marks(<tt class="literal">!</tt>). For example:</p><blockquote><pre class="code">$doc = 'c:\test\test.xls';$x1 = Win32::OLE->GetObject($doc);</pre></blockquote><p>This code creates an Excel instance based on an Excel file. It is notalways clear what type of object <tt class="literal">GetObject</tt> willreturn from a document since applications may register for more thanone document type (e.g., worksheets, charts, macro files, etc. forExcel). You can use <tt class="literal">QueryObjectType</tt> on an objectto get the class name of the object.</p></div></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_19.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="ch23_02.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr><tr><td align="left" valign="top" width="228">22.19. Win32 Extensions</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">23.2. Automation Methods and Properties</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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