This example creates a PTF called noop. This is a minimalist use case of a client interface.

CREATE PACKAGE noop_package 
 AS  
  FUNCTION describe(t IN OUT DBMS_TF.table_t)  
   RETURN DBMS_TF.describe_t; 
  
  PROCEDURE fetch_rows;  
 
END noop_package;  

CREATE PACKAGE BODY noop_package  
AS  
  FUNCTION describe(t IN OUT DBMS_TF.table_t)  
   RETURN DBMS_TF.describe_t AS  
  BEGIN  
    RETURN NULL;  
  END;  
 
  PROCEDURE fetch_rows  
  AS  
  BEGIN  
    RETURN;  
  END;  
END noop_package;  

CREATE FUNCTION noop (t TABLE)  
  RETURN TABLE PIPELINED ROW POLYMORPHIC USING noop_package; 

SELECT *  
FROM noop(scott.emp) 
WHERE deptno =10

WITH e  
 AS (SELECT *  
     FROM scott.emp  
     NATURAL JOIN scott.dept 
     WHERE dname = 'SALES')  
SELECT t.*  
FROM noop(e) t