$$database_handle = DBI->connect((
                     map {
                       my $s="database_$_";
                       exists $arguments{$_} ?
                              $arguments{$_} :
                              $caller->$s()
                         }
                     (qw(data_source_name username password))
                    ), {Taint=>$arguments{taint}||$caller->database_taint}
                   ) or die "Could not connect to the database: $DBI::errstr" unless defined $$database_handle;