Hi!
It seems it is explained here
http://technet.oracle.com/docs/products/oracle8i/doc_library/817_doc/appdev.817/a76939/adg10pck.htm#6142
excerpt:
PL/SQL lets you overload packaged (but not stand-alone) functions. You can
use the same name for different functions if their formal parameters differ
in number, order, or datatype family.
N.B. Nothing about return values
and finally here more clearly:
http://technet.oracle.com/docs/products/oracle8i/doc_library/817_doc/appdev.817/a77069/07_subs.htm#1057
excerpt:
Finally, you cannot overload two functions that differ only in return type
(the datatype of the return value) even if the types are in different
families. For example, you cannot overload the following functions:
DECLARE
...
FUNCTION acct_ok (acct_id INTEGER) RETURN BOOLEAN IS
BEGIN ... END;
FUNCTION acct_ok (acct_id INTEGER) RETURN INTEGER IS
BEGIN ... END;
Gints Plivna
Jared.Still@r
adisys.com To: Multiple recipients of list ORACLE-L
<[EMAIL PROTECTED]>
Sent by: cc:
root@fatcity. Subject: PLS-307 error - makes no sense
com
2001.08.23
23:09
Please
respond to
ORACLE-L
Dear List,
First off, this is kind of long, so don't start reading unless you have
some time. :)
I've run into this before, and now I can't remember how to resolve it.
( database is 8.1.7.0 )
The Signature of a procedure or function is made up of:
1. function or procedure name
2. data types of arguments
3. mode of arguments ( IN, OUT, IN OUT )
4. return value in the case of a function
There are some other special cases, but this is enough for this discussion.
The documentataion is quite clear on one thing; changing the name of an
argument will *not* change the signature.
Here's some code to demonstrate
==========================
create or replace package ftest
is
function login(
username_in varchar2
, password_in varchar2
) return boolean;
function login(
username_in varchar2
, password_in varchar2
) return varchar2;
end;
/
show errors package ftest
create or replace package body ftest
is
function login(
username_in varchar2
, password_in varchar2
) return boolean
is
begin
return true;
end;
function login(
username_in varchar2
, password_in varchar2
) return varchar2
is
login_success boolean := false;
begin
login_success := login(
username_in
, password_in
);
if login_success then
return 'LOGIN';
else
return 'NOLOGIN';
end if;
end;
end;
/
show errors package body ftest
===========================
Try to compile this and you will get :
Errors for PACKAGE BODY FTEST:
LINE/COL
---------------------------------------------------------------------------------
ERROR
----------------------------------------------------------------------------------------------------
21/3
PL/SQL: Statement ignored
21/21
PLS-00307: too many declarations of 'LOGIN' match this call
The signatures of these two function are different: one returns a boolean
and the other returns a varchar. The login() function that returns a
varchar
should be able to call a function of the same name and arguments that
returns a boolean. But it doesn't work.
The code below does work. Notice the two changes. The login() function
that returns a boolean now has a prefix of 'b_' on it's input arguments.
The login() function that returns a varchar now uses named parameters to
call the login() function that returns a boolean.
Both of these changes are necessary to make this work.
Any ideas?
Thanks
Jared
====================================================
create or replace package ftest
is
function login(
b_username_in varchar2
, b_password_in varchar2
) return boolean;
function login(
username_in varchar2
, password_in varchar2
) return varchar2;
end;
/
show errors package ftest
create or replace package body ftest
is
function login(
b_username_in varchar2
, b_password_in varchar2
) return boolean
is
begin
return true;
end;
function login(
username_in varchar2
, password_in varchar2
) return varchar2
is
login_success boolean := false;
begin
login_success := login(
b_username_in => username_in
, b_password_in => password_in
);
if login_success then
return 'LOGIN';
else
return 'NOLOGIN';
end if;
end;
end;
/
show errors package body ftest
====================================
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author:
INET: [EMAIL PROTECTED]
Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
San Diego, California -- Public Internet access / Mailing Lists
--------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from). You may
also send the HELP command for other information (like subscribing).
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author:
INET: [EMAIL PROTECTED]
Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
San Diego, California -- Public Internet access / Mailing Lists
--------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from). You may
also send the HELP command for other information (like subscribing).
