AW: link list returned from service program

depends on the linked list implementation. i used to code a header for the linked list where i save state of the iteration.

-----Ursprüngliche Nachricht-----
Von: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx] Im Auftrag von Lim Hock-Chai
Gesendet: Mittwoch, 12. März 2008 15:50
An: RPG programming on the AS400 / iSeries
Betreff: RE: link list returned from service program

Any suggestion on how getNextCustomer would know what is the next
customer that caller is asking for? I guess I could add a 2nd parameter
that tells getNextCustomer what the last customer was. In this case
getNextCustomer will need to do a search for every call.



-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of john e
Sent: Wednesday, March 12, 2008 7:39 AM
To: RPG programming on the AS400 / iSeries
Subject: RE: link list returned from service program

Encapsulation is a good thing.

Indeed. As a general rule, return a pointer to the program to the
structure which is managed by the service program itself (i.e. allocated
and destroyed).
The program only knows about the pointer, it knows nothing about the
internal structure. Then pass this pointer as the first argument to
procedures "GetNextCustomer", "GetParentCustomer". And if you put all
the code like this that belongs to the Customer entity into one
well-named serviceprogram then we even have a bit of OO here.

Subject: RE: link list returned from service program
Date: Wed, 12 Mar 2008 08:17:19 -0400
From: WiltC@xxxxxxxxxx
To: rpg400-l@xxxxxxxxxxxx

Actually, I take back what I said a minute ago about your idea being

reasonable.

Is there any reason for actually passing back the linked list?

You could easily keep the link list implementation hidden, and just
expose procedures like GetNextCustomer(), GetParentCustomer() that
would allow the callers of the service program access to the data

while hiding the fact you're using a linked list.

Encapsulation is a good thing.

Charles Wilt
Software Engineer
CINTAS Corporation - IT 92B
513.701.1307

wiltc@xxxxxxxxxx

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx]
On Behalf Of Lim Hock-Chai
Sent: Tuesday, March 11, 2008 6:00 PM
To: RPG programming on the AS400 / iSeries
Subject: RE: link list returned from service program

To create customer family tree. Our customer master file has customer

number field and parent customer number field. Every now and then, we

need to know all the descendants of a customer number. So..., I
created a export procedure that accept a customer number as a
parameter. It will return the caller a link list that represent the
customer's family tree.




-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Alan Campin
Sent: Tuesday, March 11, 2008 4:48 PM
To: rpg400-l@xxxxxxxxxxxx
Subject: Re: link list returned from service program



Lim Hock-Chai wrote:

I'm just curious to know if I've an export procedure that returns a
link list to the caller, how safe is it to continue to use the link
list after the service program is destroyed from the activation

group?

I have to ask. Why are you returning a linked list from a service
program?

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