#!/your/perl/here
use strict;
use warnings;

use Getopt::Declare;

my $option_spec = qq{
# note: required tab between last argument and description
	-x <x0> [<x1> <x2> <x3>]	-x takes 1 or 4 args
		[required]
	
	-y <y0> [<y1> <y2>]		-y takes 1 or 3 args
		[required]
	
	-z <z0> [<z1>]	-z takes 1 or 2 args
		[required]
	
	At least one of these options is required, and all are mutually exclusive.
	[mutex: -x -y -z]
	
Examples:

	$0 -x zero one two three
	
	$0 -y zero alpha beta
	
	$0 -z zero last_but_not_least
};

my $options = Getopt::Declare->new( $option_spec )
  or die "\n**** Error processing command line options, terminating $0\n";

sub do_something { print "@_\n"; }

if ( $options->{'-x'} )
{
	if ( defined( $options->{'-x'}{'<x1>'} ) )
	{
		do_something("-x", $options->{'-x'}{'<x0>'},
                           $options->{'-x'}{'<x1>'}, 
                           $options->{'-x'}{'<x2>'}, 
                           $options->{'-x'}{'<x3>'} ) if $options->{'-x'}
	}
	else
	{
		do_something("-x", $options->{'-x'}{'<x0>'} );
	}
}		

if ( $options->{'-y'} )
{
	if ( defined( $options->{'-y'}{'<y1>'} ) )
	{
		do_something("-y", $options->{'-y'}{'<y0>'},
                           $options->{'-y'}{'<y1>'}, 
                           $options->{'-y'}{'<y2>'} ) if $options->{'-y'}
	}
	else
	{
		do_something("-y", $options->{'-y'}{'<y0>'} );
	}
}		
if ( $options->{'-z'} )
{
	if ( defined( $options->{'-z'}{'<z1>'} ) )
	{
		do_something("-z", $options->{'-z'}{'<z0>'},
                           $options->{'-z'}{'<z1>'} ) if $options->{'-z'}
	}
	else
	{
		do_something("-z", $options->{'-z'}{'<z0>'} );
	}
}