if ($self->{_can_do_transactions}) {

     # If RaiseError is true, begin_work() will:
     #     return true if a new transaction was started
     #     croak if already in a transaction
     #     croak if transactions not supported
     #
     local $dbh->{RaiseError} = 1;
     my $started_a_new_transaction = 0;
     eval { $started_a_new_transaction = $dbh->begin_work };

     eval {
         $code->(@_);
         $dbh->commit if $started_a_new_transaction;
     };
     if ($@)
     {
         my $msg = $@;
         eval { $dbh->rollback } if $started_a_new_transaction;
         die $msg;
     }
 }
 else
 {
     code_that_touches_db();
 }