Range in Getopt

[Ammu]

Hi i am using Getopt to accept the debug parameters.But it sholud be within the range 1-4.Can anyone tell me how to include the ange in Getopt?

Getopt::Long::GetOptions(
   
   'd=i' => \$_debug)
or usage("Invalid commmand line options.");

[james2vegas]

You can evaluate options with Getopt::Long using a custom subroutine, like this:



use Getopt::Long;
my $_debug;
GetOptions('d=i' => sub {
        $_debug = $_[1];
        ($_debug > 0 && $_debug <= 4) or die "Invalid Debug Level ($_d
+ebug)"
    } ) and warn $_debug;



GetOptions catches the die and throws it as a warning and returns false. When using the custom subroutine, you need to handle assigning to the variable for your option yourself.

[roho]

I like your solution, but when no -d parameter is present, the following warning is displayed:

Warning: something's wrong at C:\tmp\getopt-range.pl line 15.

This appears to be a warning from Getopt::Long. I tried adding return 1 if !defined @_; at the top of the sub but the warning persists.

[james2vegas]

That is because while the d option's value is required, the d option itself is not, check the definedness of $_debug afterwards:



use Getopt::Long;
my $_debug;
GetOptions('d=i' => sub {
        $_debug = $_[1];
        ($_debug > 0 && $_debug <= 4) or die "Invalid Debug Level ($_d
+ebug)"
    } ) or exit 1;

die "Debug Level is required" unless defined $_debug;
warn "Debug Level is $_debug\n";


or set a default value before GetOptions:



use Getopt::Long;
my $_debug = 0;
GetOptions('d=i' => sub {
        $_debug = $_[1];
        ($_debug > 0 && $_debug <= 4) or die "Invalid Debug Level ($_d
+ebug)"
    } ) or exit 1;

warn "Debug Level is $_debug\n";

[NetWallah]

One option is to use the "Specifying other parameter variable types" in Getopt::Declare.

This allows declarative regex matching on the parameter.

[dasgar]

Here's my typical approach to using Getopt::Long. First I assign a default value to the variables that will be used in GetOptions(). Then I test the values of those variables. If they are acceptable values, proceed. Otherwise, stop and give an error message.

Applied to your question, here's what my (untested) code would look like:

use strict;
use warnings;

use Getopt::Long;

my $debug = "";

GetOptions( 'd=i' => \$debug);

if ($debug eq "") {
  # -d flag was not used
}
else {
  if (($debug < 1) && ($debug > 4)) {
    # -d flag used, but value is not acceptable
    my $msg = "The value of '$debug' is not valid for -d option.\n";
    $msg = "The -d option only accepts the values between 1 and 4.\n"
    die "$msg";
  }
}

Might not be the best or more elegant solution, but it should work and it makes sense to me.

[Discipulus]

i usually do like this:


my $needed_param = 'need_default';
my $debug = 0; # default value numeric and not ""

# getting params with getopt with a strict syntax
# id est: if GetOptions fail may be better the program does NOT run at
+ all
&help()if( ! GetOptions( 
                         'needed=s' => \$needed_param,
                         # [..]
                         'd=i' => \$_debug 
                       ) or ! $needed_param );

#then adjust values to a default or a maximum as needed

$debug > 3 ? $debug = 3 : $debug ;

sub help { "$0 -n [-d [0-3]] ... "}

hope this help
L*

[toolic]

Another way (stealing james2vegas's die message):

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

my $_debug = 1; # or whatever default you want it to be
GetOptions('d=i' => \$_debug) or die("Invalid commmand line options.")
+;

die "Invalid Debug Level ($_debug)" if $_debug<1 or $_debug>4;

print "\$_debug = $_debug\n";