SQL & PL/SQL

Hello, I have code like this:

  procedure getAllTasks(o_cursor                      in out PKG_APPLICATION.rc,
                        in_filter_project_id          in T_FCT_TASK.project_id%type default -1,
                        in_filter_scope_id            in T_FCT_TASK.scope_id%type default -1,
                        in_filter_user_creator_id     in T_FCT_TASK.user_creator_id%type default -1,
                        in_filter_priority_id         in T_HST_TASK.priority_id%type default -1,
                        in_filter_status_id           in T_HST_TASK.status_id%type default -1,
                        in_filter_user_responsible_id in T_HST_TASK.user_responsible_id%type default -1,
                        in_pagination_first           in integer,
                        in_pagination_last            in integer) is
    v_query varchar2(4000) := v_query_allTasks || v_query_whereFilter;
  begin
    PKG_APPLICATION.setPagination(v_query);
  
    PKG_LOG.debug('query: ' || v_query, PCK);
  
    open o_cursor for v_query
      using in_filter_project_id, in_filter_scope_id, in_filter_user_creator_id, in_filter_priority_id, in_filter_status_id, in_filter_user_responsible_id, in_pagination_last, in_pagination_first;
  end;

The v_query variable contains:

SELECT * FROM (SELECT A.*, ROWNUM AS RNUM
                  FROM (
    SELECT task_id, project_id, project_name, scope_id, scope_name, user_creator_id, user_creator_login, title, description,
           priority_id, priority_name, status_id, status_name, user_responsible_id, user_responsible_login, due_date,
           last_modified_by_id, last_modified_by_login, last_modified
      FROM V_FCT_TASK
    WHERE project_id          = decode(:1, -1, project_id, :1)
      and scope_id            = decode(:2, -1, scope_id, :2)   
      and user_creator_id     = decode(:3, -1, user_creator_id, :3)   
      and priority_id         = decode(:4, -1, priority_id, :4)   
      and status_id           = decode(:5, -1, status_id, :5)   
      and user_responsible_id = decode(:6, -1, user_responsible_id, :6)   
  ) A
                  WHERE ROWNUM <= :LAST)
            WHERE :FIRST <= RNUM

Note, that placeholders :1, :2, ... :5 appear 2 times in the query.

Is there a more elegant way to tell that *:1* should be replaced by in_filter_project_id, *:2* by in_filter_scope_id without actually having these variables twice in the USING clause? If not, why do placeholders have name, if you can only reference them by position(order)?

Thanks for all replies.