RE: Adding pointers to RPG language.

["Bob Cozzi \(RPGIV\)" <cozzi@xxxxxxxxx>]

If we didn't have pointers in RPG IV, it would be so difficult to call
the various C runtime library functions that we've been exploiting.

I agree that if people fall into a groove of using pointers for things
like link lists, that is going too far, and an array, or multiple
occurrence data structure might be safer.

Bob Cozzi
cozzi@rpgiv.com
Visit the on-line  Midrange  Developer  forum at: http://www.rpgiv.com


> -----Original Message-----
> From: rpg400-l-admin@midrange.com [mailto:rpg400-l-admin@midrange.com]
On
> Behalf Of Mel Rothman
> Sent: Friday, January 11, 2002 5:32 PM
> To: rpg400-l@midrange.com
> Subject: Re: Adding pointers to RPG language.
>
> I think we are more in agreement than not.
>
> Yes, RPG pointer support is nothing like C pointer support.  However,
I was
> commenting about no pointer support versus what has been implemented.
If the
> RPG IV compiler team were to implement additional pointer support, it
would
> make my day! :-)
>
> Regarding pointers being overused, I can comment only for myself, and
I plead
> "not guilty."  I use them to accomplish what can't be accomplished
nearly as
> easily in other ways or when they give me significant performance
advantages
> over the alternatives.
>
> I agree that many RPG programmers have trouble with pointers, as do
many C,
> Pascal, etc. programmers.  Pointers are tools, like any other.  The
user has
> to learn how to use them properly or suffer the consequences.
Programmers
> that find pointers beyond their grasp, can and should, as you said,
choose not
> to use them.
>
> I still think the pointer we have today was a very good idea and thank
you
> very much for whatever part you played in bringing it to us.
>
> Cheers,
>
> Mel Rothman
> IBM eServer Custom Technology Center (eCTC), Rochester, Minnesota
> http://www-1.ibm.com/servers/eserver/iseries/service/ctc/
>
>
> Hans Boldt wrote:
> >
> > Mel wrote:
> > >Hans, I don't think "adding pointers to the language was a bad
idea."
> > >
> > >You should be taking credit, not blame, for adding them.
> > >
> > >Many things that would be difficult or impossible to do without
pointers
> > >are relatively easy to do with them.  For example: dynamically
allocated
> > >storage, using many system APIs and C functions, navigating complex
> > >structures, handling blocks of data larger than 32767 bytes, etc.
> >
> > Two points:
> >
> > First, RPG pointer support is nothing like pointers in, say, C.  In
> > C, pointers are typed, and so the compiler can complain about type
> > mismatches, which can save lots of potential headaches.  Pointers in
> > RPG are untyped.  It's a lot more difficult to debug pointer
problems
> > in RPG than in C.  (And C is hard enough as it is sometimes!)
> >
> > Second, I believe pointers may well be overused in RPG.  Sure,
> > they're great when you have to call some API.  But beyond that, I
> > wonder if they're being used just because they might offer some
> > "cool", "geeky" way to implement some function.
> >
> > For example, if you need to manage some varying sized amount of
data,
> > there are several different ways to handle it.  If you're dealing
> > with a compute-bound application (like a compiler), a reasonable
> > approach would be to use a linked list, using pointers and malloc's.
> > But application programs typically are I/O bound, not compute bound,
> > and so program performance is less of a concern.  In this case, a
> > table in a database would be easier to understand and easier to
> > maintain, along with other advantages, like persistence.
> >
> > In other words, just because you have some capability, it doesn't
> > mean you have to use it.
> >
> > The essence of good software engineering is not just knowing how to
> > use some tool, but also knowing how NOT to use it.
> >
> > >rpg400-l messages indicate that many RPG IV programmers are using
them
> > >to great advantage.
> >
> > ... and often having lots of problems with them.  :-(
> >
> > Cheers!  Hans
> >
> > Hans Boldt, ILE RPG Development, IBM Toronto Lab, boldt@ca.ibm.com
> >
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