Change function to work for date data type

Question

I have found the below function form the AstTom page. This function works perfectly when i pass varchar datatype and I am wondering what do i need to change here of course the datatype inoder
for this function to accept date value. example I want to pass (05/21/2010, 04/23/2010) as a date data type and
--create your type
create or replace type varcharTableType as table   of varchar2 (255); 
CREATE OR REPLACE FUNCTION tplcp.in_varchar (p_string IN VARCHAR2)
   RETURN varchartabletype
AS
   l_string   LONG             DEFAULT p_string || ',';
   l_data     varchartabletype := varchartabletype ();
   n          NUMBER;
BEGIN
   LOOP
      EXIT WHEN l_string IS NULL;
      n := INSTR (l_string, ',');
      l_data.EXTEND;
      l_data (l_data.COUNT) := LTRIM (RTRIM (SUBSTR (l_string, 1, n - 1)));
      l_string := SUBSTR (l_string, n + 1);
   END LOOP;
   RETURN l_data;
END in_varchar;
CREATE OR REPLACE PROCEDURE planholderslist (
   p_letting_date   IN       VARCHAR2,
   p_results        OUT      sys_refcursor
AS
BEGIN
   OPEN p_results FOR
      SELECT DISTINCT DECODE (TRIM (MIN (j.route)),
                              NULL, 'N/A',
                              TRIM (MIN (j.route))
                             ) routenumber,
                      l.lcontid contractid, (q.cdescr) jobdescription,
                      INITCAP (q.clocat1 || q.clocat2) LOCATION,
                      SUBSTR (q.cprojnum, 1, 10) projectnumber,
                         SUBSTR (l.letting, 3, 2)
                      || '-'
                      || SUBSTR (l.letting, 5, 2)
                      || '-'
                      || SUBSTR (l.letting, 1, 2) lettingdate
                 FROM vendor v,
                      vendaddr r,
                      letprop l,
                      planhold p,
                      proposal q,
                      project j,
                      propproj k,
                      bidlet bd
                WHERE v.vendor = r.vendor
                  AND k.contid = q.contid
                  AND k.pcn = j.pcn
                  AND l.lcontid = k.contid
                  AND p.vendor = v.vendor
                  AND l.letting = p.letting
                  AND (TO_CHAR (bd.datelet, 'MM/DD/YY') IN (
                                      SELECT COLUMN_VALUE
                                        FROM TABLE (in_varchar (p_letting_date)
                  AND l.CALL = p.CALL
                  AND r.addrnum = p.billto
                  AND bd.letting = l.letting
             GROUP BY q.cdescr,
                      q.clocat1,
                      q.clocat2,
                      bd.letting,
                      l.letting,
                      l.lcontid,
                      q.cprojnum
             ORDER BY lettingdate;
END planholderslist;
/

Answer 1

three or even four dates passed to the parameter.4 date parameters are still easy to code for. Use an IN clause.
Just do something like this:
SQL> select * from t;
D
05-JAN-2010 00:00:00
15-MAR-2010 00:00:00
09-SEP-2010 00:00:00
07-DEC-2010 00:00:00
SQL> create or replace
  2  procedure find_date (rc out sys_refcursor
  3                      ,p1 in date
  4                      ,p2 in date default null
  5                      ,p3 in date default null
  6                      ,p4 in date default null
  7                      ) as
  8  begin
  9    open rc for
10       select d
11       from   t
12       where  d in (p1,p2,p3,p4);   -----<<< notice this line
13  end;
14  /
SQL> var results refcursor
SQL> exec find_date(:results, to_date('05-JAN-2010'));
PL/SQL procedure successfully completed.
SQL> print results
D
05-JAN-2010 00:00:00
SQL> exec find_date(:results, to_date('05-JAN-2010'),to_date('09-SEP-2010'));
PL/SQL procedure successfully completed.
SQL> print results
D
05-JAN-2010 00:00:00
09-SEP-2010 00:00:00
SQL> exec find_date(:results, to_date('05-JAN-2010'),to_date('09-SEP-2010'), sysdate);
PL/SQL procedure successfully completed.
SQL> print results
D
05-JAN-2010 00:00:00
09-SEP-2010 00:00:00
SQL> exec find_date(:results, to_date('05-JAN-2010'),to_date('09-SEP-2010'), to_date('15-MAR-2010'), to_date('07-DEC-2010'));
PL/SQL procedure successfully completed.
SQL> print results
D
05-JAN-2010 00:00:00
15-MAR-2010 00:00:00
09-SEP-2010 00:00:00
07-DEC-2010 00:00:00