cat p.pl
perl p.pl -h   -p 1 ; \
perl p.pl -p q -h   ; \
perl p.pl -p   -h   ; \
perl p.pl -p q      ; \
perl p.pl -p        ; \
perl p.pl -p 3

use strict; use warnings;

#  May or may not work wit previous version(s).
use Getopt::Long 2.38;

my ( $h );
Getopt::Long::Configure( 'pass_through' );
GetOptions( 'help' => \$h );
die "HELP" if $h;

my ( $p );
Getopt::Long::Configure( 'nopass_through' );
Getopt::Long::GetOptionsFromArray
( \@ARGV
, 'p=i'  => \$p
) or die;

printf "p: %s\n" , defined $p ? $p : 'undef';

__END__

HELP at p.pl line 10.
HELP at p.pl line 10.
HELP at p.pl line 10.
Value "q" invalid for option p (number expected)
Died at p.pl line 14.
Option p requires an argument
Died at p.pl line 14.
p: 3