Re: RPG,COBOL or JAVA

[boldt@xxxxxxxxxx]

Buck Calabro wrote:
>I think that this is very well said.  An aside is
>that RPG IV/ILE RPG can help you learn OO while
>you work, rather than have to learn OO AND a new
>language AND a new environment (GUI) all at the
>same time.

I have to disagree with this.  New features of
RPG IV, such as prototyped procedures, allow you
to apply the technique of "modular programming",
which became popular in the early 80's.  Object
oriented programming goes well beyond modular
programming.  Being well-versed in modular
programming offers little advantage when faced
with fundamental OO concepts such as inheritance.

I'll try to explain with a practical example.
Say you want to implement some interactive dialog.
Using a non-OO style, you would lay out the
widgets on the screen and monitor for events on
those widgets.  Using OO techniques, you would
extend the behavior of the widgets.  For example,
rather than using a TextField to display a part
number, you would define a new widget called,
say, PartNumberField, which extends TextField.
This widget would inherit all the functionality
of TextField, but would implement the rules
specific to part numbers.  This is an incredibly
powerful concept and I believe is difficult to
understand fully until you actually try it.  I've
noticed myself while programming in Java that
it is sometimes easier in the short term to not
extend an existing class, but eventually, I find
that extending a class makes things easier
overall.

To summarize my point:  Inheritance is a very
fundamental characteristic of OO programming and
cannot be fully appreciated without experiencing
OO.  Using a non-OO language, like RPG IV, can
never prepare you for OO.

Cheers!  Hans

Hans Boldt, ILE RPG Development, IBM Toronto Lab, boldt@ca.ibm.com


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