sub define {
    my $self = shift;
    my $type = shift || croak "No type name";

    unless ($template) {
        local $/ = undef;
        $template = <DATA>;
    }

    my ($code, $parent, $subclass) =
        ($template, __PACKAGE__, __PACKAGE__ . "\::$type");

    $code =~ s,##PACKAGE##,$subclass,g;
    $code =~ s,##PARENT##,$parent,g;

    {
        my $WARNING = '';
        local $SIG{__WARN__} = sub { $WARNING = "@_" };
        eval $code;
        croak "Failed to create subclass: $subclass - $WARNING$@" if
            $WARNING || $@;

        croak "Problem with subclass: $subclass - cannot new()" unless
            $subclass->can(qw/new/);
    }

    print STDERR "Created type: $type\n";
}