Subj : Translating CASE from BASIC to C++
To   : All
From : Mike Luther
Date : Wed Feb 07 2001 01:17 am

I've been faced with the job of translating everything from PowerBASIC to C++ 
in order to survive.  Like it or not I have to provide application 
cross-platform compatibility between DOS, OS/2 and .. WIN-xx, if I go into 
that.  I've also been advised by one client that the Feds told them that here 
in the USA, 7 years of support have to be given for any old system when a new 
one is implemented in certain medical applications with medical records.  I 
don't represent that as gospel, only what I have been told to expect... ;)

Now .. the only way I can seemingly, perhaps, gain seven years of 
cross-platform interoperability between OS/2, and DOS ... and shudder,WIN-xx .. 
is with WATCOM V11(b) which I licensed along with the books, and where it may 
go as version (c) etc., a long time ago.

So ..

I'm about 60% through writing an auto-translator from PowerBASIC 3.5 source to 
Watcom V11 (b).  It's been educational.  One of the things that has been a 
stumbling block to me is the use of CASE in BASIC where the switch logic is 
based not on numeric conditionals, but alpha conditionals.

This surfaced in the OS/2 echo a bit ago with something that Sarah replied to.  
I posted it in the Watcom Forum.  I'd like to attempt to re-look at the issue 
here to see if anyting inspirational shows here please:


     1.) How can you handle CASE translations from BASIC to C++
         for OS/2, with emphasis on WATCOM V11(b) as the toolset?

     2.) SWITCH functions only with numeric logic, as I now think
         is the only way it works.  That's what I learned in the
         Watcom Forum when this question was posed there.

     3.) Based on what I learned from the Watcom Forum, my intitial
         translator algorithim was writtne to simply back-level
         all SELECT CASE in BASIC to the crude IF / THEN logic.

         Write the translator so that it converts the SELECT CASE
         to form a conditional master variable, based on what
         was used for the SELECT conditional variable.

         Re-design SELECT CASE as a parade of IF/THEN constructs.

That works fine for numeric-based stuff.  In my limited knowledge of C++, it 
can degenerate into lots and lots of lines of code for non-numeric logic. It 
still seems to me that handling strings ain't near so easy in C++ as it is in 
BASIC, sigh..

Using the stock WATCOM libraries, remember this has to work across, DOS,OS/2 
and .. shudder .. likely WIN-xx too, what do we do?  Suggestions would be 
appreciated.  However, that's really unfair, isn't it? ;)

I think Sarah is faced with this same problem as well, but maybe not in WATCOM 
V11, but some other compiler.  Thus the problem is generic?  But is sure is 
OS/2 programming related, at least to me and I suspect others.


Thanks ..


Mike @ 117/3001

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