sub _setter_getter_maker
{
  my $subname = shift;
  my $funcref;

  $funcref = eval<<"END";
  sub
  {
    my(\$self, \$$subname) = \@_;
    \$self->{'$subname'} = \$$subname if defined \$$subname;
    return \$self->{'$subname'};
  };
END

  return $funcref;
}