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<html><head><title>Tie::Array, Tie::StdArray (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="ch08_214.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_216.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr></table></div><h2 class="sect1">8.215. Tie::Array, Tie::StdArray</h2><p><a name="INDEX-1583" /><a name="INDEX-1584" /><a name="INDEX-1585" />Provides methods for array-tyingclasses. (See the <em class="emphasis">perltie</em> manpage for thefunctions needed for tying an array to a package.) The basicTie::Array package provides stub DELETE and EXTEND methods andimplements PUSH, POP, SHIFT, UNSHIFT, SPLICE, and CLEAR in terms ofbasic FETCH, STORE, FETCHSIZE, and STORESIZE.</p><p>Tie::StdArray inherits from Tie::Array and provides the methodsneeded for tied arrays implemented as blessed references to an"inner" Perl array. It causes tiedarrays to behave like standard arrays, allowing for selective methodoverloading.</p><p>See the <em class="emphasis">perltie</em> manpage for more detailedinformation and for examples. To write your own tied arrays, use thefollowing required methods.</p><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>TIEARRAY</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>TIEARRAY <em class="replaceable">classname</em>, <em class="replaceable">list</em></pre><p>Constructor. This method is invoked by the command<tt class="literal">tie</tt> <em class="replaceable"><tt> @array</tt></em> ,<em class="replaceable"><tt>classname</tt></em>. Associates an array instancewith the specified class. <em class="replaceable"><tt>list</tt></em> representsadditional arguments needed to complete the association. Shouldreturn an object of a class that provides the remaining methods.</p></div><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>CLEAR</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>CLEAR <em class="replaceable">this</em></pre><p>Clears all values from the tied array associated with object<em class="replaceable"><tt>this</tt></em>.</p></div><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>DESTROY</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>DESTROY <em class="replaceable">this</em></pre><p>Normal object destructor.</p></div><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>EXTEND</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>EXTEND <em class="replaceable">this</em>, <em class="replaceable">count</em></pre><p>Doesn't need to do anything. Provides informationthat the array will likely grow to have<em class="replaceable"><tt>count</tt></em> entries.</p></div><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>FETCH</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>FETCH <em class="replaceable">this</em>, <em class="replaceable">index</em></pre><p>Retrieves the data item in <em class="replaceable">index</em> for thetied array associated with object <em class="replaceable"><tt>this</tt></em>.</p></div><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>FETCHSIZE</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>FETCHSIZE <em class="replaceable">this</em></pre><p>Returns the number of items in the tied array associated with object<em class="replaceable"><tt>this</tt></em>.</p></div><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>POP</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>POP <em class="replaceable">this</em></pre><p>Removes the last element from the array and returns it.</p></div><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>PUSH</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>PUSH <em class="replaceable">this</em>, <em class="replaceable">list</em></pre><p>Appends elements of <em class="replaceable">list</em> to the array.</p></div><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>SHIFT</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>SHIFT <em class="replaceable">this</em></pre><p>Removes and returns the first element of the array, shifting theremaining elements down.</p></div><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>SPLICE</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>SPLICE <em class="replaceable">this</em>, <em class="replaceable">offset</em>, <em class="replaceable">length</em>, <em class="replaceable">list</em></pre><p>Performs the equivalent of a <em class="emphasis">splice</em> on thearray. Returns a list of the original<em class="replaceable"><tt>length</tt></em> elements at the specified offset.The arguments are:</p><dl><dt><i><em class="replaceable"><tt>offset</tt></em></i></dt><dd>Optional. Defaults to <tt class="literal">0</tt>; if negative, counts backfrom the end of the array.</p></dd><dt><i><em class="replaceable"><tt>length</tt></em></i></dt><dd>Optional. Defaults to the rest of the array.</p></dd><dt><i><em class="replaceable"><tt>list</tt></em></i></dt><dd>May be empty.</p></dd></dl></div><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>STORE</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>STORE <em class="replaceable">this</em>, <em class="replaceable">index</em>, <em class="replaceable">value</em></pre><p>Stores value of a data item into <em class="replaceable">index</em> forthe tied array associated with object<em class="replaceable"><tt>this</tt></em>. If the resulting array is largerthan the class's mapping for the array,<tt class="literal">undef</tt> should be returned for new positions.</p></div><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>STORESIZE</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>STORESIZE <em class="replaceable">this</em>, <em class="replaceable">count</em></pre><p>Sets the total number of items in the tied array associated withobject <em class="replaceable"><tt>this</tt></em> to<em class="replaceable"><tt>count</tt></em>. If this makes the array larger thanthe class's mapping for the array, then<tt class="literal">undef</tt> should be returned for new positions. If itmakes the array smaller than the mapping, then entries beyond<em class="replaceable"><tt>count</tt></em> should be deleted.</p></div><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>UNSHIFT</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>UNSHIFT <em class="replaceable">this</em>, <em class="replaceable">list</em></pre><p>Inserts <em class="replaceable">list</em> elements at the beginning ofthe array, moving existing elements up to make room.</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_214.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_216.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr><tr><td align="left" valign="top" width="228">8.214. Thread::Specific</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">8.216. Tie::File</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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