mandog has asked for the wisdom of the Perl Monks concerning the following question:

I've gotten in the habit of creating error messages like this: 

use strict ;
use Getopt::Long;

my ($username,$password,$group);
my $err_msg='';

GetOptions('u=s' => \$username,'g=s'=> \$group,
           'p=s'=>\$password);

$err_msg.="missing -u username\n" unless $username;
$err_msg.="missing -g group\n" unless $group;
$err_msg.="missing -p password\n" unless $password;

die "$err_msg" if $err_msg;

[download]

It works without obvious errors, but somehow this feels wrong...

Am I missing something...



email: mandog

Replies are listed 'Best First'.
Re: .= $err_msg
by particle (Vicar) on Apr 27, 2002 at 03:18 UTC
    i'd do something like: 
    #!/usr/bin/perl -w
use strict;

use Getopt::Long;


my( $username, $password, $group );
my %params = (
    'u=s' => \$username,
    'p=s' => \$password,
    'g=s' => \$group,
);

sub usage
{
    die << "USAGE";
Usage: 
  $0 -u username -p password -g group [-others]

Description:
  whatever...

USAGE
}

usage() unless( GetOptions( %params ) );
for( values %params )
{
    usage() unless defined ${ $_ };
}

    [download]
    • this captures the return code from GetOptions (please do this!)
    • i tend not to customize usage information (one doc for everyone, and they should read it!)
    • there's no $err_msg variable in file scope for the rest of the program (remember to use undef when you're done with it)

    ~Particle *accelerates*

[reply]
[d/l]
      That last loop just begs for trimming: 

      grep { not defined $$_ } values %params
    or die usage();

      [download]

      Well, maybe it's just me. But I really think that judicious grep usage is much clearer than equivalent for loops.

          -- Chip Salzenberg, Free-Floating Agent of Chaos

[reply]
[d/l]
Re: .= $err_msg
by BUU (Prior) on Apr 27, 2002 at 02:11 UTC
    I might prefer doing it with a loop and pushing all the new error messages onto an 'error' array, but thats personal taste.
[reply]

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