SQL> var c REFCURSOR;
SQL> ed
Wrote file afiedt.buf

  1  declare
  2   r dept%rowtype;
  3  begin
  4   open :c for 'select * from dept';
  5   fetch :c into r;
  6   fetch :c into r;
  7* end;
SQL> /

PL/SQL procedure successfully completed.

SQL> print :c

    DEPTNO DNAME          LOC
---------- -------------- -------------
        30 SALES          CHICAGO
        40 OPERATIONS     BOSTON

SQL> print :c

SQL> print :c

    DEPTNO DNAME          LOC
---------- -------------- -------------
        30 SALES          CHICAGO
        40 OPERATIONS     BOSTON

SQL> var c
variable   c
datatype   REFCURSOR
SQL> print c
SP2-0625: Error printing variable "c"
SQL> ed
Wrote file afiedt.buf

  1  declare
  2   r dept%rowtype;
  3  begin
  4   if :c%isopen then
  5     dbms_output.put_line('Open');
  6   else
  7     dbms_output.put_line('close');
  8   end if;
  9* end;
SQL> /
close

PL/SQL procedure successfully completed.

SQL>

FUNCTION f(p_w  int) RETURN sys_refcursor is
...
  begin
   case when p_w =0 ... then 
        open cur_app for t... ;
   case when p_w =1 ... then 
        open cur_app for t_a... ;
   else
        open cur_app for dual ... ;
   end;
return cur_app;

declare
   n sys.odcinumberlist;
   v sys.odcivarchar2list;
begin
   execute immediate 'select 100 n, ''str'' v from dual connect by rownum <= 10' bulk collect into n, v;
   for i in 1 .. n.count
   loop
      dbms_output.put_line(n(i) || ' ' || v(i));
   end loop;
end;