Pass SQL into a Function

Question

Is it possible to pass a SQL into a Function
DECLARE
   f        sys_refcursor;
   RESULT   NUMBER;
   FUNCTION myfunction (r sys_refcursor)
      RETURN NUMBER
   IS
   BEGIN
      RETURN TO_NUMBER (TO_CHAR (r.dt, 'DD'));
   END;
BEGIN
   OPEN f FOR
      SELECT SYSDATE dt
        FROM DUAL;
   RESULT := myfunction (f);
   CLOSE f;
END;

Answer 1

Yes you are allowed to pass ref cursor but they have to processed the way you processur cursor i.e. OPEN, FETCH, CLOSE.
See demonostration of working code:
SQL>DECLARE
  2     f        sys_refcursor;
  3     RESULT   NUMBER;
  4
  5     FUNCTION myfunction (r sys_refcursor)
  6        RETURN NUMBER
  7     IS
  8     v_currDate DATE;
  9
10     BEGIN
11        IF r%ISOPEN THEN
12          FETCH r INTO v_currDate;
13        END IF;
14
15        RETURN TO_NUMBER (TO_CHAR (v_currDate, 'DD'));
16     END;
17  BEGIN
18     OPEN f FOR
19        SELECT SYSDATE dt
20          FROM DUAL;
21
22     RESULT := myfunction (f);
23
24     DBMS_OUTPUT.PUT_LINE('Date : ' || RESULT );
25
26     CLOSE f;
27  END;
28  /
Date : 23
PL/SQL procedure successfully completed.
{code}