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<html><head><title>Carp (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="Carp"><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="ch32_02.htm"><img src="../gifs/txtpreva.gif" alt="Previous" border="0"></a></td><td align="center" valign="top" width="171"><a href="ch32_01.htm">Chapter 32: Standard Modules</a></td><td align="right" valign="top" width="172"><a href="ch32_04.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">32.3. Carp</h2><a name="INDEX-5804"></a><a name="INDEX-5805"></a><p><blockquote><pre class="programlisting">use Carp;croak "We're outta here!";use Carp qw(:DEFAULT cluck);cluck "This is how we got here!";</pre></blockquote>The <tt class="literal">Carp</tt> module lets you write modules whosefunctions report errors the way built-in operators reporterrors--from the perspective of the users of your module. The<tt class="literal">Carp</tt> module supplies routines that you use muchlike the standard built-in functions <tt class="literal">warn</tt> and<tt class="literal">die</tt>, but that change the filename and line numberso it looks like the error originated from the user's code instead ofyour code. In short, <tt class="literal">Carp</tt> is great way tomisdirect blame.</p><p>There are actually four functions. The <tt class="literal">carp</tt>function works like the <tt class="literal">warn</tt> operator, but withcaller-relative filename and line number information. The<tt class="literal">croak</tt> function works like <tt class="literal">die</tt>does--raising an exception--but again gives caller-relativeinformation. If you prefer a longer lament, use<tt class="literal">cluck</tt> and <tt class="literal">confess</tt> instead of<tt class="literal">carp</tt> and <tt class="literal">croak</tt> respectively, andyou'll get a full stack backtrace reporting who called whom and withwhat arguments (in the library with a lead pipe, no doubt). You haveto import <tt class="literal">cluck</tt> explicitly, because it's notnormally exported. People don't often want full stack traces on merewarnings, for some reason.</p><!-- 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="ch32_02.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="ch32_04.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0"></a></td></tr><tr><td align="left" valign="top" width="172">32.2. Benchmark</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">32.4. CGI</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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