Accessor methods for inside-out objects

I have just been looking at Class::Accessor, recommended by Simon Cozens at http://www.perl.com/pub/a/2006/01/26/more_advanced_perl.html. It automagically generates accessor methods, but appears to rely on a %fields type approach, and will not work on inside-out objects.
I got to thinking. Actually generalised accessors for inside-out objects are not that difficult, not need some ev[ai]l doings.

   my %speed;
   my %reg;
   my %owner;
   my %mileage;

   sub set {
      my ($self, $attr, $value) = @_;
      my $key = refaddr $self;

      my $hashref;
      eval "\$hashref = \\\%$attr";

      if ( !defined $hashref ) {
         carp 'Invalid attribute name';
         return;
      }
        
      $hashref->{$key} = $value;
   }

   sub get {
      my ($self, $attr, $value) = @_;
      my $key = refaddr $self;

      my $hashref;
      eval "\$hashref = \\\%$attr";

      if ( !defined $hashref ) {
         carp 'Invalid attribute name';
         return;
      }
        
      return $hashref->{$key};
   }

BTW: I also found how to do formatting: <pre>...</pre>