Well, another command-line-parsing-module ... but I must say, I prefer Getopt::Long which is a core module and therefore available everywhere. In addition to that, there are plenty of tests for Getopt::Long, it is more flexible and easier to use (eg. no need to define subs that match the arguments by hand). Apart from that, your module has a couple of problems, eg. it doesn't need Exporter, has a inconsistent interface (why can I say my @singles = $a->getSingles; but not my %keyvals = $a->getKeys), ...

To underline my point, I have rewritten the script given in your POD using Getopt::Long. The only difference is that '-4Adam;Barbara' is now written as two arguments -4 and 'Adam;Barbara'. Btw, your script as given doesn't compile, it uses croak without use Carp; - I have replaced that with a simple warn.

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

my $usage_msg = <<'EOHELP';

greeter is a sample program for Argdom.pm.

--help | -h displays this help message and quits.
-o outfile is the file to which the output is written. Can be many, as
+ in -o f1 -o f2 -o f3. `-' means the STDOUT (default).
-xclaim means the output should be exclamatory.
-4 X;Y;Z means the greeting should be for X, Y, and Z. Default is ``Wo
+rld'' and yourself!.
any other args are the greeting. Default is "Hello"./;

EOHELP

my $xclaim   = 0;
my $usage    = 0;
my $greeting = '';
my $forWhom  = 'World;to you';
my @outs;

GetOptions ("h|help"  => \$usage,
            "xclaim!" => \$xclaim,
            "4=s"     => \$forWhom,
            "o=s"     => \@outs,
) or die $usage_msg;

if ($usage) {
    print $usage_msg;
    exit;
}

$greeting .= $_ foreach @ARGV;
$greeting = 'Hello' unless $greeting;
@outs = qw/-/ unless @outs;

my $output = '';
$output .= "$greeting, $_" . ($xclaim ? '!' : '.') . "\n"
    for (split /;/, $forWhom);
foreach my $outfile (@outs) {
    if ($outfile eq '-') {
        print $output;
    } else {
        open my $outfh, '>', $outfile or warn "Could not open $outfile
+ for writing: $!";
        print $outfh $output;
        close $outfh;
    }
}
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