Help required on Getopt::Long

[ghosh123]

Hi Monk,
In my program, I am using the module Getopt::Long My intension is that if the user chooses "--help", the program should show the help message without bothering whether other options has been used or not. My program (say, test.pl) :

 
use Getopt::Long
my $abc;
my $help;
 
GetOptions ( "abc=s" => \$abc,
                   "help" => \$help
                 );
 
if ($help) { print "This is help message\n" ; exit ;}
 
if ($abc) { print "You have choosen \"abc\" as $abc" };

If I run this:
1. test.pl -help
Output: This is help message

2. test.pl -abc ABC
Output : You have choosen abc as ABC

3. test.pl -abc -help
Output: You have choosen abc as -help

Out of the above results 1 & 2 are fine, but 3 is not as I want. I understand what's happening here $abc is assigned as "-help", but don't have idea how to implement it properly so that in the 3rd it would print like " This is help message" .

Can anybody help please ?
Thanks and regards

[Anonymous Monk]

This works as intended, --abc requires a string argument, so there is no way to make an exception for your case without breaking it for everyone else. I propose two work-arounds:

Mention in the documentation that --help should come as first option (circular problem is some cases).

Filter @ARGV for --help yourself before you call GetOptions.

[zeni]

This is because -help is treated as string for the option "abc". even though '=' is not used the next string is tied for "abc" option.

Also, when i executed this code, i got the following error:

Undefined subroutine &main::Getoptions called.

Always include use strict and use warnings in your code. And the subroutine should be GetOptions

[Anonymous Monk]

read "Getoptions" as "GetOptions". Sorry for the typo.

[Anonymous Monk]

pass_through configuration option and &GetOptionsFromArray has a solution -- complete with option requirement type checking -- for you ...

cat p.pl
perl p.pl -h   -p 1 ; \
perl p.pl -p q -h   ; \
perl p.pl -p   -h   ; \
perl p.pl -p q      ; \
perl p.pl -p        ; \
perl p.pl -p 3

use strict; use warnings;

#  May or may not work wit previous version(s).
use Getopt::Long 2.38;

my ( $h );
Getopt::Long::Configure( 'pass_through' );
GetOptions( 'help' => \$h );
die "HELP" if $h;

my ( $p );
Getopt::Long::Configure( 'nopass_through' );
Getopt::Long::GetOptionsFromArray
( \@ARGV
, 'p=i'  => \$p
) or die;

printf "p: %s\n" , defined $p ? $p : 'undef';

__END__

HELP at p.pl line 10.
HELP at p.pl line 10.
HELP at p.pl line 10.
Value "q" invalid for option p (number expected)
Died at p.pl line 14.
Option p requires an argument
Died at p.pl line 14.
p: 3

[Anonymous Monk]

Come to think of it, Getopt::Long::GetOptionsFromArray( \@ARGV , ... ) can be replaced with GetOptions( ... ).

[uday_sagar]

Problem Solved!

Just replace '=' with ':' at line 5

Here is the code.

use Getopt::Long;
my $abc;
my $help;
 
GetOptions ( "abc:s" => \$abc,
                   "help" => \$help
                 );
 
if ($help) { print "This is help message\n" ; exit ;}
 
if ($abc) { print "You have choosen \"abc\" as $abc" };

You can get more information on Getopt::Long here

[Anonymous Monk]

Replacing equal sign with colon alone does not solve the problem. It changes the problem by making the value for option abc optional instead of being required; equals sign impose that a value need to be specified ...

  = type [ desttype ] [ repeat ]
    The option requires an argument of the given type.

  .
  .
  .

  : type [ desttype ]
    Like "=", but designates the argument as optional.  If
    omitted, an empty string will be assigned to string
    values options, and the value zero to numeric options.

[Anonymous Monk]

".. equals sign impose that a value need to be specified ..." -- self.

GAAH! Make that "... equals sign imposes that a value is need to be specified ...".

[vagabonding electron]

This seems to work (an idea from Re: Help required on Getopt::Long: Just add a line:

grep {/help/} @ARGV and print "This is help message\n" and exit;

above GetOptions.

[Anonymous Monk]

It is not robust enough in case "help" is part of a string of a value to another option or an argument passed.

[ww]

but that seems to be easily remedied with anchors in the expression (and -- for ease of illustration -- using a defined array rather than @ARGV):

#!/usr/bin/perl
use 5.014;

my $count;
my @arr = qw/helper abc help def helpless helpful whelp help/;
$count = grep {/^help$/}@arr and print "This is a help message. ";    
+# Note1
say "\$count: $count";

# This is a help message. $count: 2

^Note1: can also be written $count = grep /^help$/, @arr ....