#!/use/bin/env perl

use Getopt::Long;
use Getopt::Long::Confused;

GetOptions(\my %h
    ,qw(a:s b c d)
    ,qw(e=s f g h)
    ,qw(i:o j k l m n)
    ,qw(o=o p q r s t)
    ,qw(u:f w x)
    ,qw(y=f z)
    );
my %option=(
    # after placing options in this order 
    #                => check with this regex
    'a b c d *'      => '^a( [bcd]) $'       # a requires one of b, c or d
    ,'e f g h *'     => '^e( [fgh])? $'      # e requires at most one of f g or h
    ,'i j k l m n *' => '^$'                 # don't allow i and o options
    ,'o p q r s t *' => '^$'                    # in this example
    ,'u v w x *'     => '^u( v)|( w x) $'    # u requires v OR w and x
    ,'y z *'         => '^y z $'             # y requires z
    );
   
if (my $warning=Getopt::Long::Confused::check(\%h,\%option)) {
    die $warning;
    }

### 'done!'
exit;