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

my %args;
my $result = GetOptions (
          "c=s" => \&COMP1,
          "t=s" => sub {
            if($args{c}) {
                COMP2(@_); # COMP2 will not be called if option c is null?
            } else {
                warn 'Error: arg -t without preceding -c: processing terminated';
                die '!FINISH';
            }
          },
          '<>' => sub {print "\nThat is not a valid parameter\n";},
    );
die "Error: argument processing did not complete successfully" unless($result);
exit(0);


sub COMP1 {
    print "Option -$_[0] is value=$_[1]\n";
    $args{$_[0]} = $_[1];
}

sub COMP2 {
    print "Option -$_[0] is value=$_[1]\n";
    $args{$_[0]} = $_[1];
}