sub Fetch_w_callback{ # Main DBI retrieval mechanism----
   my ($sql, $callback) = @_;
   my $state = $_[2] ||= {}; # ** This THIRD param is CALL-by-ref **
   $debug{SQL} = $sql;
   (my $sth=$dbh->prepare($sql))->execute();
   
   $state->{ROW} = 0; 
   while (my $row = $sth->fetchrow_hashref()){
      $debug{ROW} = $state->{ROW}++;
      last if $callback->($row,$state) < 0; # Return negative to quit
   }
   $sth->finish;
 }
#....

#Call sequence ... (In this case, used with CGI ...
 Fetch_w_callback( $sql, 
      sub{ # This sub gets called once per row returned....
          my ($dbRow,$LocalState) = @_;
          push @{$LocalState->{RAWDATA}},$dbRow ; # Raw data is available later
          $RawDataOnly and return  $render_helper->(@_); # Called ONCE per row, on Rawdata.
          if ($LocalState->{ROW} == 1 ){ # No Rows yet
              $fieldname[0] eq "*" and @fieldname = keys %$dbRow;
              print Tr( {-class=>"tableHeader"},
                         map ({td(b($_))}   @fieldname), $extrafields->()) . "\n";
              $_ = lc($_) for @fieldname; # DBI apparently only LC's
          }
          print Tr(  map( {td($render_helper->($dbRow->{$_},$_,$dbRow))} @fieldname),$extrafields->(@_) ) . "\n";  
         }
       , $state);