package Class;

sub new {
   my $class = shift;
   my $self  = {X => shift, Y => shift,};

   return bless $self, $class;
}

sub x {
   my $self = shift;
   if (@_) {
       $self->{'X'} = @_[0];
   }
   return $self->{'X'};
}
sub y {
   my $self = shift;
   if (@_) {
       $self->{'Y'} = @_[0];
   }
   return $self->{'Y'};
}
1;

package Main;

my $o = Class->new(20);
print $o->x() . "/" . $o->y() . "\n";   # 20/
$o = Class->new(40, 50);
print $o->x() . "/" . $o->y() . "\n";   # 40/50
$o->x(300);
print $o->x() . "/" . $o->y() . "\n";   # 300/50