perl的Getopt::Long和pod::usage ？

来源：

http://www.cnblogs.com/itech/archive/2012/08/07/2627267.html

代码：

需要显式地定义变量且初始化。例如optionX。

如果没有定义变量且显式初始化，且没有在命令行指定选项，则选项对应的变量将为未定义。

#!/bin/perl-5.8.3/bin/perl$
use warnings;
use strict;

use Data::Dumper;
use Getopt::Long;
use Pod::Usage;

our $g_opts;
our $optionX=''; #if not defined in command line, it will be empty string
sub parse_opts{
    my $result = GetOptions(
                    "optionA=s" => $g_opts->{'optionA'},#string
                    "optionB=s" => $g_opts->{'optionB'},#string
                    "optionC=i" => $g_opts->{'optionC'},#integer
                    "optionD=f" => $g_opts->{'optionD'},#float
                    "optionX=f" => $optionX,
                    "optionY=f" => $optionY,
                    "verbose"   => $g_opts->{'verbose'},#flag
                    "quiet"     => sub { $g_opts->{'verbose'} = 0 },
                    "help|?"    => $g_opts->{'help'}
                  );
    if(!($g_opts->{'optionA'})){
        &pod2usage( -verbose => 1);#exit status will be 1
    }
    if($g_opts->{'help'}){
        &pod2usage( -verbose => 1);#exit status will be 1
    }
}

&parse_opts();
print("
$optionX
");
print($optionY); #if not defined in command line, it will be undefined
print($g_opts->{"optionB"});

foreach my $key (keys %{$g_opts}){
  if(!$g_opts->{$key}) {next;} 
  print($key . "=" . $g_opts->{$key} . "
");
  }
41 exit(0);
43 
45 __END__46 47 =head1 NAME
49 sample - Using Getopt::Long and Pod::Usage
51 =head1 SYNOPSIS
53 sample [options] [args ...]
55 Options:56 57    -optionA         optionA 
   -optionB         optionB
   -optionC         optionC 
   -optionD         optionD 
   -verbose         verbose 
   -quiet           noverbose 
   -help            brief help message
65 =head1 OPTIONS
67 =over 868 69 =item B<-help>70 71 Print a brief help message and exits.72 73 =back
75 =head1 DESCRIPTION
77 B<This program> will read the given input file(s) and do something
useful with the contents thereof.79 80 =cut