package Location;
use 5.008001;
use strict;
use vars '$AUTOLOAD';
use warnings;
use Carp;
use UNIVERSAL qw/ isa /;

use integer; #we use integer coordinates
use constant nl=>"\n";
use constant X=>0; # these are the array fields
use constant Y=>1;

##</code><code>##

# defaults
{
    my $default_location=[ 
	0, 
	0 
	];
    sub get_default_location{
	return [$default_location->[X],$default_location->[Y]];
    }

   sub get_default_X{
	return $default_location->[X];
    }

   sub get_default_Y{
	return $default_location->[Y];
    }
}

##</code><code>##

sub new{
    use integer;
    my ($self,$x,$y)=@_;

# if $x is an arrayref use this 

    if (isa($x,'ARRAY')){
	return bless $x,$self;
    }
# otherwise try the parameters or use defaults
    return bless[
	$x||get_default_X,
	$y||get_default_Y
	],$self;
}

##</code><code>##

sub get_location{
    my $self=shift;
    return [$self->[X],$self->[Y]];
}

sub get_X{

    my $self=shift;
    return $self->get_location->[X];
}

sub get_Y{
    my $self=shift;
    return $self->get_location->[Y];
}

##</code><code>##

sub set_location{
    my ($self,$x,$y)=@_;
    if(isa($x,"PLocation")){
	$self->[X]=$x->get_X;
	$self->[Y]=$x->get_Y;
    }       
       elsif(defined $x and defined $y){
	$self->[X]=$x;
	$self->[Y]=$y;
    }   
       else {
	   croak "Insufficient Arguments: set_location(PLocation->new($x,$y)) or set_location($x,$y)".nl;
       }
}

sub set_X{
    my ($self,$x)=@_;
    $self->[X]=$x;
}

sub set_Y{
    my ($self,$y)=@_;
    $self->[Y]=$y;
}
# so far so nice
1;

##</code><code>##

use integer; #we use integer coordinates
use constant nl=>"\n";
use constant X=>0; # these are the array fields
use constant Y=>1;
# overload => thats new !
use overloead '<=>' => 'compare';

##</code><code>##

sub compare {
    my ($loc1,$loc2,$rev)=@_;
    croak "Cant do this with autoloaded comparison\n" if $rev;
    if($loc1->get_X < $loc2->get_X  and $loc1->get_Y< $loc2->get_Y){ 
        return 1;
    }
    elsif($loc1->get_X > $loc2->get_X  and $loc1->get_Y> $loc2->get_Y
    ){ 
        return -1;
}
    elsif($loc1->get_X = $loc2->get_X  and $loc1->get_Y= $loc2->get_Y
    ){ 
        return 0;
    return ;
}