sub get {
  my($self,$attr) = @_;
  my $return_val;
  
  # if valid attribute, assign it as a return value
  if($attr =~ m/\A\w+\z/) {
    my $eval_string = sprintf '$return_val = $%s_of{refaddr $self};', $attr;
    eval $eval_string;
  }
  # otherwise, carp a warning
  else {
    carp("Invalid attribute '$attr'");
  }
  
  return $return_val;
}

##</code><code>##

if($attr =~ m/\A\w+\z/) {
  $return_val = ${$attr}{refaddr $self};
}