Extract Procedure,Package,Package Body,Function in Oracle

set scan on
set pages 0
set feedback off
set heading off
set verify off
set lines 300
set trims on

set term on
prompt +--------------------------------------------+
prompt DESCRIPTION:
prompt ============
prompt This script will extract source code for the following source types:
prompt 1. PACKAGE
prompt 2. PACKAGE BODY
prompt 3. FUNCTION
prompt 4. PROCEDURE
prompt The source code will be spooled into a file named after the source name
prompt USAGE:
prompt =====
prompt follow the prompts ...
prompt +---------------------------------------------+
accept proc_name  prompt "Enter Procedure Or Package Name: "
accept proc_owner prompt "Enter The Owner Name: "
accept type prompt "Enter type Of the source [PACKAGE, PACKAGE BODY, PROCEDURE, FUNCTION]: "
set term off

SELECT DECODE(ROWNUM,1,'CREATE OR REPLACE '||text,text)
FROM   dba_source
WHERE  name  = UPPER('&&proc_name')
AND    owner = UPPER('&proc_owner')
AND    type  = UPPER('&type')
ORDER BY line

spool &&proc_name..sql
/
prompt /
spool off

ed &&proc_name

undefine proc_name