Writing Presentation Manager Programs in Modula-2

by Chris Barker

August 4, 1990

The files contained in this zipped file constitute my attempt to write OS/2
Presentation Manager programs using JPI's Modula-2 for OS/2 version 2.0. I
am both new to Modula-2 and to programming for the Presentation Manager.
Previously I have been programming extensively with Turbo Pascal and less
extensively with Turbo C.

Since the preponderance of documentation for writing PM code is in C, I
thought the world might benefit from some examples written in another
language such as Modula-2. I have taken a very clearly written book,"OS/2
Presentation Manager - Programming Primer" by Asael Dror and Robert Lafore,
and adapted their "C" examples to Modula-2. Hopefully, my adaptions have
been correct!

Personally, I find the protective environment of Pascal/Modula-2 (i.e.
strong type checking, promoting modular projects, etc.) a much more
comfortable and rewarding programming experience. I am a very high level
minded kind of programmer that would prefer to adapt and reuse mine or
someone else's code (OOP?) to get a job done rather than wallowing down in
the internals of my computer's CPU. I am always impressed by the
blindingly fast routines of a Zen assembler master like Michael Abrash, but
I'd rather work on a higher level. Jeff Duntemann is programmer I look up
to.

Speaking of OOP, my other reason for being attracted to JPI's M2 for OS/2
is its inclusion of object extensions to Modula-2. The example program,
PMTEST, is my own cursory attempt at encapsulating some of the complexity
of PM programming using OOPS. I hope to extend this and leverage some real
power. I hope to hear from others that may be trying the same thing.

While adapting these programs, I came across a few puzzling issues that
JPI's fairly sparse documentation didn't enlighten me on. In the cases
where I got stumped, I spent a lot of time scanning JPI's WIN.DEF file for
possible answers. Sometimes I was lucky, other times I wasn't. For
example, I am still puzzled by JPI's implementation of PM's two message
queues. I have often found that the "correct" M2 code was the opposite of
the "C" code (e.g. using mp2 instead of mp1). I am probably missing
something and would love to be enlightened. Also, has anyone figured out
the equivalent M2 routine for the "C" macro: #define SHORT1FROMMP(mp)
((USORT)(ULONG)(mp))? I have tried for example: SHORTCARD(LONGCARD(mp1)),
but this does not return the correct values.

So far I have gotten through chapter six of the book and will hopefully
update this file as I adapt further examples. Please read the header
comments in each program before you run the program so you will understand
what each is supposed to do. I hope these examples will encourage others
to try a hand at PM programming using Modula-2.


Writing OS/2 PM Programs in Modula-2 August 4, 1990 Page 2



I would love to hear from other programmers. Please send a message to me,
Chris Barker, at one of the following:

- Compuserve ID: 72261,2312

- Pete Norloff's OS/2 Shareware BBS - (703) 385-4325

- Max's Doghouse BBS - (703) 548-7849

The above two BBS carry the Fidonet OS/2 echo which I read
regularly.

- Programmer's Corner - (301) 596-1180

- CPCUG Mix (Window Sig) BBS - (301) 738-9060

Enjoy!








































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