Questions about Getopt::Long 1

[whn]

Please take a look at the piece of code below:

#!/usr/bin/perl

use strict;
use warnings;
use Getopt::Long;

my ($debug, $emailAddr, $fussy, $fussier);
GetOptions( [b]# This is line 8[/b]
  "d" => \$debug,
  "e=s" => \$emailAddr,
  "fussy" => \$fussy,
  "fussier" => \$fussier,
) || die;

if($fussy) {
  print "\$fussy = $fussy\n";
}
if($fussier) {
  print "\$fussier = $fussier\n";
}
if($debug) {
  print "\$debug = $debug\n";
}
if($emailAddr) {
  print "\$emailAddr = $emailAddr\n";
}
print "$0 exit...\n";
exit;

And some sample runs and my questions are list below in red:

% ./tt.pl -d
$debug = 1
./tt.pl exit...

% ./tt.pl -e
Option e requires an argument
Died at ./tt.pl line 8.

% ./tt.pl -e -d
$emailAddr = -d [b][COLOR=red]<-- This is a bug. How to fix it?[/color][/b]
./tt.pl exit...

% ./tt.pl -fussy
$fussy = 1
./tt.pl exit...

./tt.pl -ff
Unknown option: ff
[b]Died at ./tt.pl line 8.[/b]

% ./tt.pl -fussier
$fussier = 1
./tt.pl exit...

% ./tt.pl -fussi
$fussier = 1 [b][COLOR=red]<-- How can this happen? I'd expect to see the error: Unknown option: fussi[/color][/b]
./tt.pl exit...

Many thanks!!

 

[whn]

It seems that GetOptions() does sort of wild cards expansion thing.

#!/usr/bin/perl

use strict;
use warnings; 
use Getopt::Long;

my ($ab, $ac, $xyz);
GetOptions(
  "ab" => \$ab,
  "ac" => \$ab,
  "xyz" => \$xyz,
) || die;

if($ab) {
  print "\$ab = $ab\n";
}
if($ac) {
  print "\$ac = $ac\n";
}
if($xyz) {
  print "\$xyz = $xyz\n";
}
print "$0 exit...\n";
exit;

Test runs:

% ./tt.pl -a
Option a is ambiguous (ab, ac)
Died at ./tt.pl line 8.

% ./tt.pl -x
$xyz = 1
./tt.pl exit...

Not sure if there is a way to disable GetOptions()'s wild cards expansion functionality?

 

[rharsh]

Did you read the perdocs on Getopt::Long? There's a lot in there, but the bit below was near the top.

In the "Getting Started with Getopt::Long" section, the approximately fourth paragraph reads:

In the default configuration, options names may be abbreviated to uniqueness, case does not matter, and a single dash is sufficient, even for long option names. Also, options may be placed between non-option arguments. See "Configuring Getopt::Long" for more details on how to configure Getopt::Long.

The auto_abbrev option looks like it handles the specific behavior you were noticing.

 

[whn]

To rharsh,

Thank you for pointing out the perldoc. I just read it:

auto_abbrev
Allow option names to be abbreviated to uniqueness. Default is enabled unless environment variable POSIXLY_CORRECT has been set, in which case auto_abbrev is disabled.

But when I set the environment in the code, I don't see the difference:

$ENV{POSIXLY_CORRECT} = 1;

Am I setting the $ENV{POSIXLY_CORRECT} correctly syntax-wise? OMG, I feel so retarded.

#!/usr/bin/perl

use strict;
use warnings;
use Getopt::Long;

[b][COLOR=red]$ENV{POSIXLY_CORRECT} = 1;[/color][/b]
my ($ab, $ac, $xyz);
GetOptions(
  "ab" => \$ab,
  "ac" => \$ab,
  "xyz" => \$xyz,
) || die;

if($ab) {
  print "\$ab = $ab\n";
}
if($ac) {
  print "\$ac = $ac\n";
}
if($xyz) {
  print "\$xyz = $xyz\n";
}
print "$0 exit...\n";
exit;

Test runs:

% ./t1.pl -a
Option a is ambiguous (ab, ac)
Died at ./t1.pl line 9.

% ./t1.pl -x
$xyz = 1
./t1.pl exit...

 

[rharsh]

This is probably going to be easier... change

use Getopt::Long;

to this

use Getopt::Long qw(:config no_auto_abbrev);

 

[whn]

Thank you, rharsh. Your solution works very well.

Now, how to solve the problem below:

Sample Code:

#!/usr/bin/perl

use strict;
use warnings;
use Getopt::Long qw(:config no_auto_abbrev);

my ($email, $debug);
GetOptions(
  "d" => \$debug,
  "e=s" => \$email,
) || die;

if($email) {
  print "\$email = $email\n";
}
if($debug) {
  print "Debug mode\n";
}
print "$0 exit...\n";
exit;

And test runs:

% ./t1.pl  -e
Option e requires an argument
Died at ./t1.pl line 8.

% ./t1.pl  -e -d
$email = -d [b]//It'd be nice to post the same error message as the above.[/b]
./t1.pl exit...

Thanks!

 

[rharsh]

If you're just going to be using single letter switches, I'd suggest using GetOpt::Std.

If you're going to stick with GetOpt::Long, the module is working like it should. Your 'e' option requires a string as an argument, it got one: '-d'. So -d isn't being read as a switch/option, but as an argument for -e.

You'll probably need to do some error checking to make sure whatever is in $email actually looks like an email address. Admittedly, I haven't used getopt::long all that much, but the behavior, while not what you're looking for, seems reasonable. You can enter references to code blocks rather than a scalar to validate the variable that's being read -- and that could be used to validate the email address and then store it. There is information about this in the perldoc.

Also, this post on perlmonks might be helpful.