public function sort_prepare($pl, &$rows, $sorter)
 {
     $this->_sortinfo = $sortinfo = "_score_sort_info." . $this->score . $sorter->score;
     $this->_avginfo = $avginfo = "_score_sort_avg." . $this->score;
     $reviewer = $pl->reviewer_cid();
     $field = $this->form_field;
     foreach ($rows as $row) {
         if (($scores = $row->viewable_scores($field, $pl->contact, null)) !== null) {
             $scoreinfo = new ScoreInfo($scores);
             $row->{$sortinfo} = $scoreinfo->sort_data($sorter->score, $reviewer);
             $row->{$avginfo} = $scoreinfo->mean();
         } else {
             $row->{$sortinfo} = ScoreInfo::empty_sort_data($sorter->score);
             $row->{$avginfo} = -1;
         }
     }
     $this->_textual_sort = ScoreInfo::sort_by_strcmp($sorter->score);
 }