RE: Objects and such

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Aaron Bartell
Sent: Friday, October 19, 2007 2:06 PM
To: 'RPG programming on the AS400 / iSeries'
Subject: RE: Objects and such

To "simulate" either, you need IF/WHEN.

If I understand what you mean by IF/WHEN, I am not so sure
you DO need them to have dynamic invocation of a service
programs sub procedure. The reason I say this is because I
have done it! :-) You can use system API's to "activate" and
"bind" to a service program sub proc at runtime. I use this
approach to dispatch web service requests to the appropriate
"handler". I use the SOAPAction HTTP request header to chain
to a PF and retrive the service program and sub proc to call.

I think the IF/WHEN is there...you're just letting the DB do it for you ;)

The point is the programer has to explictly decide which function to call ahead of time given certain
input

---Overriding in RPG---
I also had a customer this week that wanted me to modify one
of my API's, and being that I couldn't get the mod made,
tested and released in time for their needs I started looking
for alternatives and stumbled across "overriding" in RPGILE.
I didn't know I could override in RPG, but it works as I
expect it (see below). I have an API named MOD_subProc that
is exported out of a *SRVPGM named 'MOD'. I wanted to
massage data before it made it to MOD_subProc, and normally
that wouldn't be a big deal, but in this case MOD_subProc was
called A LOT in this particular program. So I needed a way
to "intercept" the call, and the below does just that :-)
Maybe this would more be "super" inheritance, being that the
external MOD_subProc is being intercepted locally and then
"inherits" whatever processing was done? Yeah, I know that
is streathcing the terms a bit ;-)


H dftactgrp(*no) bnddir('MYBND')

/copy proto

/free

MOD_subProc('parm');
*inlr = *on;

/end-free



P MOD_subProc b
D MOD_subProc pi
D pValue 30a const varying

D MOD_subProcExt pr extproc('MOD_SUBPROC')
D pValue 30a const varying
/free

pValue = pValue + 'something';

// Now call the external version of MOD_subProc
MOD_subProcExt(pValue);

/end-free
P e

Cool, but I think your stretching to call this override or inheritence. <grin>


Charles


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