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📁 Perl 编程技巧大全。适合初学者阅读。
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Subject: Packages, Libraries, and Modules
Date: Wed, 29 Apr 2009 09:27:14 +0800
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" =
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    <TH align=3Dmiddle colSpan=3D3>PLEAC-Perl</TH></TR>
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    <TD vAlign=3Dbottom align=3Dleft width=3D"10%"><A accessKey=3DP=20
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<DIV class=3DSECT1>
<H1 class=3DSECT1><A name=3DPACKAGESETC>12. Packages, Libraries, and=20
Modules</A></H1>
<DIV class=3DSECT2>
<H2 class=3DSECT2><A name=3DAEN642>Introduction</A></H2>
<TABLE width=3D"100%" bgColor=3D#2f4f4f border=3D0>
  <TBODY>
  <TR>
    <TD><PRE class=3DSCREEN><FONT color=3D#f5deb3 size=3D+1><FONT =
color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#ffa500>package</FONT> <FONT =
color=3D#b2dfee>Alpha</FONT><FONT color=3D#00ffff>;</FONT>
$name =3D <FONT color=3D#00cd00>"first"</FONT><FONT =
color=3D#00ffff>;</FONT>

<FONT color=3D#ffa500>package</FONT> <FONT =
color=3D#b2dfee>Omega</FONT><FONT color=3D#00ffff>;</FONT>
$name =3D <FONT color=3D#00cd00>"last"</FONT><FONT =
color=3D#00ffff>;</FONT>

<FONT color=3D#ffa500>package</FONT> <FONT =
color=3D#b2dfee>main</FONT><FONT color=3D#00ffff>;</FONT>
<FONT color=3D#ff7f50>print</FONT> <FONT color=3D#00cd00>"Alpha is =
$Alpha::name, Omega is $Omega::name.\n"</FONT><FONT =
color=3D#00ffff>;</FONT>
Alpha is first, Omega is <FONT color=3D#ffa500>last</FONT>.
<FONT color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#ffa500>require</FONT> <FONT =
color=3D#00cd00>"FileHandle.pm"</FONT><FONT color=3D#00ffff>;</FONT>     =
       <FONT color=3D#bebebe># run-time load
</FONT><FONT color=3D#ffa500>require</FONT> <FONT =
color=3D#b2dfee>FileHandle</FONT><FONT color=3D#00ffff>;</FONT>          =
       <FONT color=3D#bebebe># ".pm" assumed; same as previous
</FONT><FONT color=3D#ffa500>use</FONT> <FONT =
color=3D#b2dfee>FileHandle</FONT><FONT color=3D#00ffff>;</FONT>          =
           <FONT color=3D#bebebe># compile-time load
</FONT>
<FONT color=3D#ffa500>require</FONT> <FONT =
color=3D#00cd00>"Cards/Poker.pm"</FONT><FONT color=3D#00ffff>;</FONT>    =
       <FONT color=3D#bebebe># run-time load
</FONT><FONT color=3D#ffa500>require</FONT> <FONT =
color=3D#b2dfee>Cards::Poker</FONT><FONT color=3D#00ffff>;</FONT>        =
       <FONT color=3D#bebebe># ".pm" assumed; same as previous
</FONT><FONT color=3D#ffa500>use</FONT> <FONT =
color=3D#b2dfee>Cards::Poker</FONT><FONT color=3D#00ffff>;</FONT>        =
           <FONT color=3D#bebebe># compile-time load
#-----------------------------
</FONT><FONT color=3D#cdcd00>1</FONT>    <FONT =
color=3D#ffa500>package</FONT> <FONT =
color=3D#b2dfee>Cards::Poker</FONT><FONT color=3D#00ffff>;</FONT>
<FONT color=3D#cdcd00>2</FONT>    <FONT color=3D#ffa500>use</FONT> <FONT =
color=3D#b2dfee>Exporter</FONT><FONT color=3D#00ffff>;</FONT>
<FONT color=3D#cdcd00>3</FONT>    <FONT color=3D#cdad00>@ISA</FONT> =3D =
<FONT color=3D#00ffff>(</FONT><FONT =
color=3D#00cd00>'Exporter'</FONT><FONT color=3D#00ffff>);</FONT>
<FONT color=3D#cdcd00>4</FONT>    <FONT color=3D#cdad00>@EXPORT</FONT> =
=3D <FONT color=3D#ff7f50>qw</FONT><FONT =
color=3D#00ffff>(</FONT>&amp;shuffle <FONT =
color=3D#cdad00>@card_deck</FONT><FONT color=3D#00ffff>);</FONT>
<FONT color=3D#cdcd00>5</FONT>    <FONT =
color=3D#cdad00>@card_deck</FONT> =3D <FONT color=3D#00ffff>();</FONT>   =
                    <FONT color=3D#bebebe># initialize package global
</FONT><FONT color=3D#cdcd00>6</FONT>    <FONT =
color=3D#ffa500>sub</FONT> <FONT color=3D#b2dfee>shuffle</FONT> <FONT =
color=3D#00ffff>{</FONT> <FONT color=3D#00ffff>}</FONT>                  =
      <FONT color=3D#bebebe># fill-in definition later
</FONT><FONT color=3D#cdcd00>7</FONT>    <FONT =
color=3D#cdcd00>1</FONT><FONT color=3D#00ffff>;</FONT>                   =
                  <FONT color=3D#bebebe># don't forget this
#-----------------------------
</FONT></PRE></FONT></TD></TR></TBODY></TABLE></DIV>
<DIV class=3DSECT2>
<H2 class=3DSECT2><A name=3DAEN645>Defining a Module's =
Interface</A></H2>
<TABLE width=3D"100%" bgColor=3D#2f4f4f border=3D0>
  <TBODY>
  <TR>
    <TD><PRE class=3DSCREEN><FONT color=3D#f5deb3 size=3D+1><FONT =
color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#ffa500>package</FONT> <FONT =
color=3D#b2dfee>YourModule</FONT><FONT color=3D#00ffff>;</FONT>
<FONT color=3D#ffa500>use</FONT> <FONT =
color=3D#b2dfee>strict</FONT><FONT color=3D#00ffff>;</FONT>
<FONT color=3D#ffa500>use</FONT> <FONT color=3D#b2dfee>vars</FONT> <FONT =
color=3D#ff7f50>qw</FONT><FONT color=3D#00ffff>(</FONT><FONT =
color=3D#cdad00>@ISA</FONT> <FONT color=3D#cdad00>@EXPORT</FONT> <FONT =
color=3D#cdad00>@EXPORT_OK</FONT> <FONT =
color=3D#cdcd00>%EXPORT_TAGS</FONT> $VERSION<FONT =
color=3D#00ffff>);</FONT>

<FONT color=3D#ffa500>use</FONT> <FONT =
color=3D#b2dfee>Exporter</FONT><FONT color=3D#00ffff>;</FONT>
$VERSION =3D <FONT color=3D#cdcd00>1.00</FONT><FONT =
color=3D#00ffff>;</FONT>              <FONT color=3D#bebebe># Or higher
</FONT><FONT color=3D#cdad00>@ISA</FONT> =3D <FONT =
color=3D#ff7f50>qw</FONT><FONT color=3D#00ffff>(</FONT>Exporter<FONT =
color=3D#00ffff>);</FONT>

<FONT color=3D#cdad00>@EXPORT</FONT>      =3D <FONT =
color=3D#ff7f50>qw</FONT><FONT color=3D#00ffff>(</FONT>...<FONT =
color=3D#00ffff>);</FONT>       <FONT color=3D#bebebe># Symbols to =
autoexport (:DEFAULT tag)
</FONT><FONT color=3D#cdad00>@EXPORT_OK</FONT>   =3D <FONT =
color=3D#ff7f50>qw</FONT><FONT color=3D#00ffff>(</FONT>...<FONT =
color=3D#00ffff>);</FONT>       <FONT color=3D#bebebe># Symbols to =
export on request
</FONT><FONT color=3D#cdcd00>%EXPORT_TAGS</FONT> =3D <FONT =
color=3D#00ffff>(</FONT>              <FONT color=3D#bebebe># Define =
names for sets of symbols
</FONT>    <FONT color=3D#00cd00>TAG1</FONT> =3D&gt; <FONT =
color=3D#00ffff>[</FONT>...<FONT color=3D#00ffff>]</FONT>,
    <FONT color=3D#00cd00>TAG2</FONT> =3D&gt; <FONT =
color=3D#00ffff>[</FONT>...<FONT color=3D#00ffff>]</FONT>,
    ...
<FONT color=3D#00ffff>);</FONT>

<FONT color=3D#bebebe>########################
# your code goes here
########################
</FONT>
<FONT color=3D#cdcd00>1</FONT><FONT color=3D#00ffff>;</FONT>             =
               <FONT color=3D#bebebe># this should be your last line
#-----------------------------
</FONT><FONT color=3D#ffa500>use</FONT> <FONT =
color=3D#b2dfee>YourModule</FONT><FONT color=3D#00ffff>;</FONT>          =
     <FONT color=3D#bebebe># Import default symbols into my package.
</FONT><FONT color=3D#ffa500>use</FONT> <FONT =
color=3D#b2dfee>YourModule</FONT> <FONT color=3D#ff7f50>qw</FONT><FONT =
color=3D#00ffff>(</FONT>...<FONT color=3D#00ffff>);</FONT>       <FONT =
color=3D#bebebe># Import listed symbols into my package.
</FONT><FONT color=3D#ffa500>use</FONT> <FONT =
color=3D#b2dfee>YourModule</FONT> <FONT color=3D#00ffff>();</FONT>       =
     <FONT color=3D#bebebe># Do not import any symbols
</FONT><FONT color=3D#ffa500>use</FONT> <FONT =
color=3D#b2dfee>YourModule</FONT> <FONT color=3D#ff7f50>qw</FONT><FONT =
color=3D#00ffff>(</FONT>:TAG1<FONT color=3D#00ffff>);</FONT>     <FONT =
color=3D#bebebe># Import whole tag set
#-----------------------------
</FONT>    <FONT color=3D#cdad00>@EXPORT</FONT> =3D <FONT =
color=3D#ff7f50>qw</FONT><FONT color=3D#00ffff>(</FONT>&amp;F1 &amp;F2 =
<FONT color=3D#cdad00>@List</FONT><FONT color=3D#00ffff>);</FONT>
    <FONT color=3D#cdad00>@EXPORT</FONT> =3D <FONT =
color=3D#ff7f50>qw</FONT><FONT color=3D#00ffff>(</FONT> F1  F2 <FONT =
color=3D#cdad00>@List</FONT><FONT color=3D#00ffff>);</FONT>        <FONT =
color=3D#bebebe># same thing
#-----------------------------
</FONT>    <FONT color=3D#cdad00>@EXPORT_OK</FONT> =3D <FONT =
color=3D#ff7f50>qw</FONT><FONT color=3D#00ffff>(</FONT>Op_Func <FONT =
color=3D#cdcd00>%Table</FONT><FONT color=3D#00ffff>);</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT>    <FONT color=3D#ffa500>use</FONT> <FONT =
color=3D#b2dfee>YourModule</FONT> <FONT color=3D#ff7f50>qw</FONT><FONT =
color=3D#00ffff>(</FONT>Op_Func <FONT color=3D#cdcd00>%Table</FONT> =
F1<FONT color=3D#00ffff>);</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT>    <FONT color=3D#ffa500>use</FONT> <FONT =
color=3D#b2dfee>YourModule</FONT> <FONT color=3D#ff7f50>qw</FONT><FONT =
color=3D#00ffff>(</FONT>:DEFAULT <FONT =
color=3D#cdcd00>%Table</FONT><FONT color=3D#00ffff>);</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT>    <FONT color=3D#cdcd00>%EXPORT_TAGS</FONT> =3D <FONT =
color=3D#00ffff>(</FONT>
        <FONT color=3D#00cd00>Functions</FONT> =3D&gt; <FONT =
color=3D#00ffff>[</FONT> <FONT color=3D#ff7f50>qw</FONT><FONT =
color=3D#00ffff>(</FONT>F1 F2 Op_Func<FONT color=3D#00ffff>)</FONT> =
<FONT color=3D#00ffff>]</FONT>,
        <FONT color=3D#00cd00>Variables</FONT> =3D&gt; <FONT =
color=3D#00ffff>[</FONT> <FONT color=3D#ff7f50>qw</FONT><FONT =
color=3D#00ffff>(</FONT><FONT color=3D#cdad00>@List</FONT> <FONT =
color=3D#cdcd00>%Table</FONT><FONT color=3D#00ffff>)</FONT>  <FONT =
color=3D#00ffff>]</FONT>,
<FONT color=3D#00ffff>);</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT>    <FONT color=3D#ffa500>use</FONT> <FONT =
color=3D#b2dfee>YourModule</FONT> <FONT color=3D#ff7f50>qw</FONT><FONT =
color=3D#00ffff>(</FONT>:Functions <FONT =
color=3D#cdcd00>%Table</FONT><FONT color=3D#00ffff>);</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT>    @<FONT color=3D#00ffff>{</FONT>
<FONT color=3D#43cd80> </FONT>
<FONT color=3D#cdcd00>$YourModule::EXPORT_TAGS</FONT><FONT =
color=3D#00ffff>{</FONT><FONT color=3D#00cd00>Functions</FONT><FONT =
color=3D#00ffff>}</FONT>
<FONT color=3D#43cd80> </FONT>
<FONT color=3D#00ffff>}</FONT>
,<FONT color=3D#43cd80> </FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT></PRE></FONT></TD></TR></TBODY></TABLE></DIV>
<DIV class=3DSECT2>
<H2 class=3DSECT2><A name=3DAEN648>Trapping Errors in require or =
use</A></H2>
<TABLE width=3D"100%" bgColor=3D#2f4f4f border=3D0>
  <TBODY>
  <TR>
    <TD><PRE class=3DSCREEN><FONT color=3D#f5deb3 size=3D+1><FONT =
color=3D#bebebe>#-----------------------------
# no import
</FONT><FONT color=3D#ffa500>BEGIN</FONT> <FONT color=3D#00ffff>{</FONT>
    <FONT color=3D#ffa500>unless</FONT> <FONT =
color=3D#00ffff>(</FONT><FONT color=3D#ffa500>eval</FONT> <FONT =
color=3D#00cd00>"require $mod"</FONT><FONT color=3D#00ffff>)</FONT> =
<FONT color=3D#00ffff>{</FONT>
        <FONT color=3D#98fb98>warn</FONT> <FONT =
color=3D#00cd00>"couldn't load $mod: $@"</FONT><FONT =
color=3D#00ffff>;</FONT>
    <FONT color=3D#00ffff>}</FONT>
<FONT color=3D#00ffff>}</FONT>

<FONT color=3D#bebebe># imports into current package
</FONT><FONT color=3D#ffa500>BEGIN</FONT> <FONT color=3D#00ffff>{</FONT>
    <FONT color=3D#ffa500>unless</FONT> <FONT =
color=3D#00ffff>(</FONT><FONT color=3D#ffa500>eval</FONT> <FONT =
color=3D#00cd00>"use $mod"</FONT><FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#00ffff>{</FONT>
        <FONT color=3D#98fb98>warn</FONT> <FONT =
color=3D#00cd00>"couldn't load $mod: $@"</FONT><FONT =
color=3D#00ffff>;</FONT>
    <FONT color=3D#00ffff>}</FONT>
<FONT color=3D#00ffff>}</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#ffa500>BEGIN</FONT> <FONT color=3D#00ffff>{</FONT>
    <FONT color=3D#ffa500>my</FONT><FONT color=3D#00ffff>(</FONT><FONT =
color=3D#9ac0cd>$found</FONT>, <FONT color=3D#cdad00>@DBs</FONT>, <FONT =
color=3D#9ac0cd>$mod</FONT><FONT color=3D#00ffff>);</FONT>
    $found =3D <FONT color=3D#cdcd00>0</FONT><FONT =
color=3D#00ffff>;</FONT>
    <FONT color=3D#cdad00>@DBs</FONT> =3D <FONT =
color=3D#ff7f50>qw</FONT><FONT color=3D#00ffff>(</FONT>Giant::Eenie =
Giant::Meanie Mouse::Mynie Moe<FONT color=3D#00ffff>);</FONT>
    <FONT color=3D#ffa500>for</FONT> <FONT color=3D#9ac0cd>$mod</FONT> =
<FONT color=3D#00ffff>(</FONT><FONT color=3D#cdad00>@DBs</FONT><FONT =
color=3D#00ffff>)</FONT> <FONT color=3D#00ffff>{</FONT>
        <FONT color=3D#ffa500>if</FONT> <FONT =
color=3D#00ffff>(</FONT><FONT color=3D#ffa500>eval</FONT> <FONT =
color=3D#00cd00>"require $mod"</FONT><FONT color=3D#00ffff>)</FONT> =
<FONT color=3D#00ffff>{</FONT>
            $mod-&gt;
import
<FONT color=3D#00ffff>();</FONT>         <FONT color=3D#bebebe># if =
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