Perl's Getopt::long and Pod::usage?

Source:

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

Code:

You need to explicitly define variables and initialize them. such as Optionx.

If you do not define a variable and explicitly initialize it, and you do not specify an option on the command line, the variable that corresponds to the option is undefined.

 
 
 1 #!/bin/perl-5.8.3/bin/perl$
 2 use warnings;
 3 use strict;
 4 
 5 use Data::Dumper;
 6 use Getopt::Long;
 7 use Pod::Usage;
 8 
 9 our $g_opts;
10 our $optionX=‘‘; #if not defined in command line, it will be empty string
11 sub parse_opts{
12     my $result = GetOptions(
13                     "optionA=s" => \$g_opts->{‘optionA‘},#string
14                     "optionB=s" => \$g_opts->{‘optionB‘},#string
15                     "optionC=i" => \$g_opts->{‘optionC‘},#integer
16                     "optionD=f" => \$g_opts->{‘optionD‘},#float
17                     "optionX=f" => \$optionX,
18                     "optionY=f" => \$optionY,
19                     "verbose"   => \$g_opts->{‘verbose‘},#flag
20                     "quiet"     => sub { $g_opts->{‘verbose‘} = 0 },
21                     "help|?"    => \$g_opts->{‘help‘}
22                   );
23     if(!($g_opts->{‘optionA‘})){
24         &pod2usage( -verbose => 1);#exit status will be 1
25     }
26     if($g_opts->{‘help‘}){
27         &pod2usage( -verbose => 1);#exit status will be 1
28     }
29 }
30 
31 &parse_opts();
32 print("\n$optionX\n");
33 print($optionY); #if not defined in command line, it will be undefined
34 print($g_opts->{"optionB"});
35 
36 foreach my $key (keys %{$g_opts}){
37   if(!$g_opts->{$key}) {next;} 
38   print($key . "=" . $g_opts->{$key} . "\n");
39   }
40 41 exit(0);
42 43 
44 45 __END__46 47 =head1 NAME
48 49 sample - Using Getopt::Long and Pod::Usage
50 51 =head1 SYNOPSIS
52 53 sample [options] [args ...]
54 55 Options:56 57    -optionA         optionA 
58    -optionB         optionB
59    -optionC         optionC 
60    -optionD         optionD 
61    -verbose         verbose 
62    -quiet           noverbose 
63    -help            brief help message
64 65 =head1 OPTIONS
66 67 =over 868 69 =item B<-help>70 71 Print a brief help message and exits.72 73 =back
74 75 =head1 DESCRIPTION
76 77 B<This program> will read the given input file(s) and do something
78 useful with the contents thereof.79 80 =cut

Perl's Getopt::long and Pod::usage?