Passing procedures/functions as arguments ?

Question

I doubt this is possible but just to make sure: can a procedure or function be passed as an argument to another (or even the same) procedure or function, like in functional programming ? This would help a lot cleaning up a convoluted if-then-else spaggeti piece of code I'm dealing with.
Thanks,
George

Answer 1

It depends on what exactly you want to do. You can pass a function as an argument to a procedure, or another function. The called function gets the result of the parameter function as the argument. You cannot pass a procedure as an argument because a procedure cannot be resolved to a scalar value or collection.
SQL> CREATE FUNCTION f (p_str IN VARCHAR2) RETURN VARCHAR2 AS
  2  l_ret VARCHAR2(100);
  3  BEGIN
  4     l_ret := 'Hello '||p_str;
  5     RETURN l_ret;
  6  END;
  7  /
Function created.
SQL> CREATE PROCEDURE p (p_str IN VARCHAR2) AS
  2  BEGIN
  3     DBMS_OUTPUT.Put_Line(p_str);
  4  END;
  5  /
Procedure created.
SQL> exec p(f('World!'))
Hello World!
PL/SQL procedure successfully completed.If you want to pass a procedure or function and have the called procedure execute that function then you will need to use dynamic sql.
HTH
John