Birgitta Hauser wrote:
For example:
If %Parms >= 3 or %Addr(Parm3) <> *NULL;
//3rd parameter is passed
EndIf;
This code is NOT valid if your program is called from ILE. From ILE you
MUST change that 'or' to be an 'and'. Otherwise it's not valid.
When it called from SQL, I don't know if it's valid. Birgitta says it
is, but I'm HIGHLY skeptical.
#1 -- since we know SQL doesn't pass a descriptor, we know that %PARMS
isn't valid. So why check it?! We already know this IF statement isn't
valid from ILE, so why include %PARMS in the check?
#2 -- How would SQL know that there's a 3rd optional parameter in your
RPG program, and therefore set the 3rd address to null?! All SQL knows
about the procedure is what you put in the 'create function' statement.
It doesn't know about the 3rd parameter, so it can't know that it
should pass a null address.
I think what Birgitta sees is that when she runs her code, she sees that
%PARMS = -1, and %ADDR(Parm3) = *NULL. She assumes that this will
always be the case. And she's right, 99.99% of the time! But she's
relying on uninitialized memory in a random spot in the computer's
memory. If that uninitialized memory happens to be an invalid pointer,
then it'll work the way she wants. And that'll be the case most of the
time, since it's unlikely that randomly encountered memory will happen
to be a valid pointer. However, in the one-in-a-million chance where
it is a valid pointer, the code will fail.
When I've discussed this situation with IBMers who work with the
database, they've suggested using a different parameter (now i'm trying
to remember what it is... the "specific name" parameter, maybe?) to
determine which of the overloaded procedures was called.
Personally, I wouldn't try to have more than one overloaded routine call
the same RPG subprocedure. Instead, I'd line them up more like this:
SQL routine: JDEDD(varchar(4), numeric(29, 9))
calls RPG: JDEDD1.
SQL routine: JDEDD(varchar(4), numeric(29, 9), varchar(1))
calls RPG: JDEDD2.
Then on the RPG side, have JDEDD1 call JDEDD2 and pass a default value
for the extra parameter.
midrange.com
