RE: OT - Shutting down an RS/6000 ?

[James Rich <james@xxxxxxxxxxx>]

On Thu, 14 Nov 2002, Joe Pluta wrote:

> > From: James Rich
> >
> > > the lack of bidirectional program parameters.
> >
> > Huh???  This has always existed.  Not identical to OS/400, but the ability
> > is certainly there.
>
> Not bidirectionally.

Oops!  I didn't see the "bidirectional" in there.  But my first example of
environment variables vs. the local data area is an example of
bidirectional parameter passing.

> <smile> I've written one or two C programs in my time, James.  I understand
> the concept of the main() methods and the argc/argv parameters.  The issue
> is bidirectionality - you can't modify those parameters and return values to
> the calling program.  This makes emulating a typical OS/400 application a
> bit tricky.

Yes, I'm sure you have.  I hope I wasn't being fecitious.  It isn't
strictly true that you can't return values to the calling program.  You
can return a value, but not multiple values (at least not when returning
from the main() function in C).

You are referring to the dynamic calls in RPG (at least I think you are),
i.e. the CALL opcode.  In C there is no real equivalent, certainly nothing
that can have multiple parameters that all get changed by the called
program (other than the environment variable example I already mentioned).
I won't argue with that.  However, it is interesting to note that more and
more people are switching to bound calls (i.e. CALLP) which are the same
as C's function calls.  Indeed, in my own programs I rarely use CALL at
all.  But I make extensive use of eval variable=function(parms).

The lack of RPG's dynamic CALL in C does not appear to me to be a
drawback (system() is not a functional equivalent).  Porting or
emulating an AS/400 RPG application in C has a lot larger hurdles than
that.  Of course using a different language might be different...

James Rich