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📁 by Randal L. Schwartz and Tom Phoenix ISBN 0-596-00132-0 Third Edition, published July 2001. (See
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<html><head><title>PerlIO::Via (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 &amp; 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="ch08_171.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="ch08_173.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr></table></div><h2 class="sect1">8.172. PerlIO::Via</h2><p><a name="INDEX-1529" />Ahelper class for PerlIO layers implemented in Perl. PerlIO::Via shipswith the Perl 5.8 source kit.</p><p>For example, you can use PerlIO::Via to call<tt class="literal">MIME::Base64::encode_base64()</tt> via<tt class="literal">open()</tt>:</p><blockquote><pre class="code">#!/usr/local/bin/perl -w;use MIME::Base64;open(my $fh, "&gt;Via(MIME::Base64)", "encode_base64");</pre></blockquote><p>PerlIO::Via implements the following methods.</p><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>CLOSE(<em class="replaceable">fh</em>)</pre><p>Returns <tt class="literal">0</tt> on success and <tt class="literal">-1</tt> onerror.</p></div><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>EOF</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>EOF(<em class="replaceable">fh</em>)</pre><p>Returns end-of-file state. The default behavior is to return a valueof <tt class="literal">FILL()</tt> or <tt class="literal">READ()</tt>.</p></div><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>ERROR</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>ERROR(<em class="replaceable">fh</em>)</pre><p>Returns error state.</p></div><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>FILENO</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>FILENO(<em class="replaceable">fh</em>)</pre><p>Returns a numeric value that represents the Unix-like filedescriptor, or <tt class="literal">-1</tt> if no file descriptor exists.</p></div><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>FILL</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>FILL(<em class="replaceable">fh</em>)</pre><p>Returns a string that will be placed in the buffer.</p></div><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>FLUSH</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>FLUSH(<em class="replaceable">fh</em>)</pre><p>Flushes any buffered write data. Returns <tt class="literal">0</tt> onsuccess and <tt class="literal">-1</tt> on error.</p></div><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>POPPED</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>POPPED([<em class="replaceable">fh</em>])</pre><p>Removes a layer from PerlIO::Via.</p></div><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>PUSHED</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>$class-&gt;PUSHED([<em class="replaceable">mode</em> [,<em class="replaceable">fh</em>]])</pre><p>Returns an object or the class, or <tt class="literal">-1</tt> on failure.<tt class="literal">PUSHED</tt> takes optional arguments for file openmode&#x2014;<tt class="literal">r</tt>, <tt class="literal">w</tt>,<tt class="literal">w+</tt>, etc.&#x2014;and takes a mandatory filehandlefor the PerlIO layer itself.</p></div><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>READ</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>READ(<em class="replaceable">buffer</em>, <em class="replaceable">len</em>, <em class="replaceable">fh</em>)</pre><p>Returns the number of octets in <em class="replaceable">buffer</em>,which must be less than or equal to <em class="replaceable"><tt>len</tt></em>.</p></div><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>SEEK</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>SEEK(<em class="replaceable">posn</em>, <em class="replaceable">where</em>, <em class="replaceable">fh</em>)</pre><p>Returns <tt class="literal">0</tt> on success and <tt class="literal">-1</tt> onerror.</p></div><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>TELL</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>TELL(<em class="replaceable">fh</em>)</pre><p>Returns the file position, without an available default.</p></div><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>UNREAD </b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>UNREAD(<em class="replaceable">buffer</em>, <em class="replaceable">fh</em>)</pre><p>Returns the number of octets from <em class="replaceable">buffer</em>that have been successfully saved.</p></div><a name="INDEX-1530" /><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>WRITE</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>WRITE(<em class="replaceable">buffer</em>, <em class="replaceable">fh</em>)</pre><p>Returns the number of octets in buffer that have beenwritten.<a name="INDEX-1530" /></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="ch08_171.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="ch08_173.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr><tr><td align="left" valign="top" width="228">8.171. PerlIO::Scalar</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">8.173. Pod::Functions</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 &copy; 2002</a> O'Reilly &amp; Associates. 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