original_string: protected static function add_to_discussion_cache($forumid, $userid, $discussion, $preference) {
          if (!isset(self::$forumdiscussioncache[$userid])) {
              self::$forumdiscussioncache[$userid] = array();
          }
  
          if (!isset(self::$forumdiscussioncache[$userid][$forumid])) {
              self::$forumdiscussioncache[$userid][$forumid] = array();
          }
  
          self::$forumdiscussioncache[$userid][$forumid][$discussion] = $preference;
      }
code: protected static function add_to_discussion_cache($forumid, $userid, $discussion, $preference) {
          if (!isset(self::$forumdiscussioncache[$userid])) {
              self::$forumdiscussioncache[$userid] = array();
          }
  
          if (!isset(self::$forumdiscussioncache[$userid][$forumid])) {
              self::$forumdiscussioncache[$userid][$forumid] = array();
          }
  
          self::$forumdiscussioncache[$userid][$forumid][$discussion] = $preference;
      }
code_tokens: protected static function add_to_discussion_cache ( $ forumid , $ userid , $ discussion , $ preference ) { if ( ! isset ( self :: $ forumdiscussioncache [ $ userid ] ) ) { self :: $ forumdiscussioncache [ $ userid ] = array ( ) ; } if ( ! isset ( self :: $ forumdiscussioncache [ $ userid ] [ $ forumid ] ) ) { self :: $ forumdiscussioncache [ $ userid ] [ $ forumid ] = array ( ) ; } self :: $ forumdiscussioncache [ $ userid ] [ $ forumid ] [ $ discussion ] = $ preference ; }
docstring: Add the specified discussion and user preference to the discussion
  subscription cache.
  
  @param int $forumid The ID of the forum that this preference belongs to
  @param int $userid The ID of the user that this preference belongs to
  @param int $discussion The ID of the discussion that this preference relates to
  @param int $preference The preference to store
docstring_tokens: Add the specified discussion and user preference to the discussion subscription cache .