my $single;
sub new {
    return $single if defined $single;
    # set up args
    $self->{dbh} = DBI->connect(@args);
    $single = bless($self, $class);
    return $single;
}

# procedural 
{
    my $dbh;
    sub get_handle {
        return $dbh if defined $dbh;

        # handle arguments
        $dbh = DBI->connect(@args);
    }

}