RE:OO-RPG -- RPG400-L

I guess I was asking the same questions as you are and I didn't believe
anybody that OO was good until I started using Java.  So I am unsure if I
could convince you of the benefits of OO.  I would recommend reading a book
called Thinking In Java to get a jump start.

Aaron Bartell


-----Original Message-----
From: Booth Martin [mailto:Booth@MartinVT.com]
Sent: Tuesday, October 01, 2002 2:04 PM
To: rpg400-l@midrange.com
Subject: Re: Qualified sub-procedures


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I am curious about something.  OO is Nirvana of course, but why?  What are
the benefit(s) about OO that make it so superb?

I ask the question because I wonder if we can do mock-OO with RPG's current
capabilities, and gain the benefits?   We don't truly care about the
features of OO, only the benefits, right?



---------------------------------------------------------
Booth Martin   http://www.MartinVT.com
Booth@MartinVT.com
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-------Original Message-------

From: rpg400-l@midrange.com
Date: Tuesday, October 01, 2002 02:02:03 PM
To: rpg400-l@midrange.com
Subject: Re: Qualified sub-procedures

Bartell, Aaron L. (TC) wrote:
> My next question to you would be why are there multiple languages that can
> do OO programming? Because somebody found a better way to do it. RPG could
> be that language that takes the next step!

Are you suggesting that an OO-RPG could be a "better way"? Sorry, I
can't see that. Unless we copy outright an existing OO language.

Why are there so many OO languages? Why are there some many types of
motor vehicles? Because some are better suited to particular tasks
than others.

>
> Why give RPG more functionality at all? Why not just have your whole shop
> move to C# or Java since they have the stuff that we are looking for? See
> where I am coming from?

I'm not sure I see your point. I've always argued that you should
use the appropriate tool for the task at hand. RPG is good at some
things, such as implementing business logic. But, not so good at
other things. (Others have argued that OO is not even suitable for
business logic. I don't agree, but I'm not going to debate *that*
point in this thread!)

>
> If I had the choice I probably would develop 90% of my new programs in
Java
> because of the flexibility, but the reality of it is that in our
corporation
> we have about 50 RPG programmers and very few Java programmers. Of those
50
> there are very few that even want to learn a OO language, but those same
> ones will want to know what the latest RPG enhancements are and start
using
> them. This brings me back to my point of wanting RPG to go more in that
> direction because that is what will allow me to use OO concepts more
because
> the RPG will adopt them more readily.

Unfortunately, there's a big learning curve in learning OO, and even
bigger if you want to learn it properly! Just having OO features in
a language does no good if you can't use them properly. And there's
a big learning curve in learning particular class libraries, which
are an important aspect of good OO languages. In the time it would
take to learn how to use an OO-RPG, you could learn Java, or any
other OO language.

I understand your point that many RPG programmers don't want
anything to do with any language not called "RPG". Many RPG
programmers also resist ILE!

In many ways, there's no reason you can't implement OO-like designs
today in RPG, if you understand OO. You could come up with some
sort of OO framework in RPG. For example, you could have a
framework where you allocate objects such that the object is
prefixed in storage by a couple of pointers, including, say, a
pointer to a class descriptor. You could define procedures that
invoke methods on the objects, and the framework could search for
the appropriate procedure based on the class hierarchy you set up.
Implementing a storage manager with an effective garbage collector
might be a bit tricky, and mixing RPG variables with objects might
be a bit of a problem, but should be doable. (However, I see that as
more of an academic exercise, and not really a practical one.)

Even without a "OO-like" framework, OO philosophy can still guide a
system design even in a procedural language. In that case, not every
programmer in the team has to understand OO, just the system architect.

Cheers! Hans
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