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<html><head><title>Saving Data Structures (Programming Perl)</title><!-- STYLESHEET --><link rel="stylesheet" type="text/css" href="../style/style1.css"><!-- METADATA --><!--Dublin Core Metadata--><meta name="DC.Creator" content=""><meta name="DC.Date" content=""><meta name="DC.Format" content="text/xml" scheme="MIME"><meta name="DC.Generator" content="XSLT stylesheet, xt by James Clark"><meta name="DC.Identifier" content=""><meta name="DC.Language" content="en-US"><meta name="DC.Publisher" content="O'Reilly & Associates, Inc."><meta name="DC.Source" content="" scheme="ISBN"><meta name="DC.Subject.Keyword" content=""><meta name="DC.Title" content="Saving Data Structures"><meta name="DC.Type" content="Text.Monograph"></head><body><!-- START OF BODY --><!-- TOP BANNER --><img src="gifs/smbanner.gif" usemap="#banner-map" border="0" alt="Book Home"><map name="banner-map"><AREA SHAPE="RECT" COORDS="0,0,466,71" HREF="index.htm" ALT="Programming Perl"><AREA SHAPE="RECT" COORDS="467,0,514,18" HREF="jobjects/fsearch.htm" ALT="Search this book"></map><!-- TOP NAV BAR --><div class="navbar"><table width="515" border="0"><tr><td align="left" valign="top" width="172"><a href="ch09_06.htm"><img src="../gifs/txtpreva.gif" alt="Previous" border="0"></a></td><td align="center" valign="top" width="171"><a href="ch09_01.htm">Chapter 9: Data Structures</a></td><td align="right" valign="top" width="172"><a href="ch10_01.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0"></a></td></tr></table></div><hr width="515" align="left"><!-- SECTION BODY --><h2 class="sect1">9.7. Saving Data Structures</h2><p><a name="INDEX-2172"></a><a name="INDEX-2173"></a><a name="INDEX-2174"></a><a name="INDEX-2175"></a><a name="INDEX-2176"></a> If you want to save your data structures for use by another programlater, there are many ways to do it. The easiest way is to use Perl's<tt class="literal">Data::Dumper</tt> module, which turns a (possiblyself-referential) data structure into a string that can be savedexternally and later reconstituted with <tt class="literal">eval</tt> or<tt class="literal">do</tt>.<blockquote><pre class="programlisting">use Data::Dumper;$Data::Dumper::Purity = 1; # since %TV is self-referentialopen (FILE, "> tvinfo.perldata") or die "can't open tvinfo: $!";print FILE Data::Dumper->Dump([\%TV], ['*TV']);close FILE or die "can't close tvinfo: $!";</pre></blockquote>A separate program (or the same program) can then read in the file later:<blockquote><pre class="programlisting">open (FILE, "< tvinfo.perldata") or die "can't open tvinfo: $!";undef $/; # read in file all at onceeval <FILE>; # recreate %TVdie "can't recreate tv data from tvinfo.perldata: $@" if $@;close FILE or die "can't close tvinfo: $!";print $TV{simpsons}{members}[2]{age};</pre></blockquote>or simply:<blockquote><pre class="programlisting">do "tvinfo.perldata" or die "can't recreate tvinfo: $! $@";print $TV{simpsons}{members}[2]{age};</pre></blockquote>Many other solutions are available, with storage formats ranging frompacked binary (very fast) to XML (very interoperable). Check out aCPAN mirror near you today!</p><a name="INDEX-2177"></a><!-- BOTTOM NAV BAR --><hr width="515" align="left"><div class="navbar"><table width="515" border="0"><tr><td align="left" valign="top" width="172"><a href="ch09_06.htm"><img src="../gifs/txtpreva.gif" alt="Previous" border="0"></a></td><td align="center" valign="top" width="171"><a href="index.htm"><img src="../gifs/txthome.gif" alt="Home" border="0"></a></td><td align="right" valign="top" width="172"><a href="ch10_01.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0"></a></td></tr><tr><td align="left" valign="top" width="172">9.6. More Elaborate Records</td><td align="center" valign="top" width="171"><a href="index/index.htm"><img src="../gifs/index.gif" alt="Book Index" border="0"></a></td><td align="right" valign="top" width="172">10. Packages</td></tr></table></div><hr width="515" align="left"><!-- LIBRARY NAV BAR --><img src="../gifs/smnavbar.gif" usemap="#library-map" border="0" alt="Library Navigation Links"><p><font size="-1"><a href="copyrght.htm">Copyright © 2001</a> O'Reilly & Associates. All rights reserved.</font></p><map name="library-map"> <area shape="rect" coords="2,-1,79,99" href="../index.htm"><area shape="rect" coords="84,1,157,108" href="../perlnut/index.htm"><area shape="rect" coords="162,2,248,125" href="../prog/index.htm"><area shape="rect" coords="253,2,326,130" href="../advprog/index.htm"><area shape="rect" coords="332,1,407,112" href="../cookbook/index.htm"><area shape="rect" coords="414,2,523,103" href="../sysadmin/index.htm"></map><!-- END OF BODY --></body></html>⌨️ 快捷键说明
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