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<html><head><title>diagnostics (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_55.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_57.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr></table></div><h2 class="sect1">8.56. diagnostics</h2><p><a name="INDEX-1362" />Providesmore descriptive diagnostics than those generated by the Perlcompiler and interpreter. Uses the longer, more explanatory errormessages found in the <em class="emphasis">perldiag</em> manpage. Can beused as a pragma or as a standalone program,<em class="emphasis">splain</em><a name="INDEX-1363" />.When used as a pragma, diagnostics affects the compilation phase ofyour program as well as the execution phase. As a standalone module,it is used to post-process errors after execution has completed.</p><p>The <em class="emphasis">splain</em> program links to<em class="emphasis">diagnostics.pm</em> to act on the standard erroroutput of a Perl program. The program's output canbe sent to a file, which is then used as input to<em class="emphasis">splain</em>, or it can be piped directly to<em class="emphasis">splain</em>. Output from <em class="emphasis">splain</em>is directed to STDOUT.</p><a name="perlnut2-CHP-8-SECT-56.1" /><div class="sect2"><h3 class="sect2">8.56.1. Options</h3><dl><dt><i><em class="emphasis">-p</em></i></dt><dd>Sets the variable <tt class="literal">$diagnostics::PRETTY</tt> to true</p></dd><dt><i><em class="emphasis">-v</em></i></dt><dd>Prints the <em class="emphasis">perldiag</em> manpage introduction, thenany diagnostic messages</p></dd></dl><p>As a pragma: </p><blockquote><pre class="code">use diagnostics [-verbose]</pre></blockquote><p>enables the use of diagnostics in your program (and enablesPerl's <em class="emphasis">-w</em> flag). Compilation isthen subject to the enhanced diagnostics, which are issued to STDERR.Set the <tt class="literal">diagnostics::PRETTY</tt> variable in a BEGINblock to provide nicer escape sequences for pagers, so your outputlooks better. The <tt class="literal">-verbose</tt> option prints the<em class="emphasis">perldiag</em> manpage introduction, then anydiagnostic messages. Functions are:</p><dl><dt><b><tt class="literal">enable</tt></b></dt><dd>Turns diagnostics on at runtime</p></dd><dt><b><tt class="literal">disable</tt></b></dt><dd>Turns diagnostics off at runtime</p></dd></dl></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_55.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_57.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr><tr><td align="left" valign="top" width="228">8.55. Devel::SelfStubber</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">8.57. 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