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Date: 26 May 93 15:29:59 GMT
From: seas.gwu.edu!mfeldman@uunet.uu.net  (Michael Feldman)
Subject: Re: XX(PL/I)  to Ada translator/lessons learned
Message-ID: <1993May26.152959.22778@seas.gwu.edu>
List-Id: <comp.lang.ada>

In article <1993May26.070218.5567@sctc.com> stachour@sctc.com (Paul Stachour) w
rites:

[other good stuff deleted]
>
>Well, not quite true.  As an experiment, I translated the same
>PL/I code into Ada.  Yes, it was still a little wierd.  Not as
>bad as the C, but still weird.  So I compiled the code (no error
>messages), and ran a few test-cases.  Bamb! Took an exception
>(arressing outside the bounds of an array) on the first test.
>
>Analysis time.  Yep, the code is "coincidentally correct".
>The element of the array that's out-of-bounds is combined
>with other data in such a way that it never affects the 
>results of the computation.
>
>But, it is a lurking boundary condition just waiting to happen.
>Some day, with some compiler, it'll lay out the data-structures
>to put that "wrong element" in the next page of memory, which
>my program doesn't own.  And then it won't be a benign error;
>it'll be a real failure.
>
I KNEW there was a good reason to hate Ada, but I couldn't put my
finger on it till now. It's all that DAMN run-time bounds checking!
Wouldn't you rather not have known about this? After all, the crash
would probably have occurred on someone else's watch... :-) :-) :-)

(Oh, what the hell. Just use pragma SUPPRESS...)

Mike Feldman
------------------------------------------------------------------------
Michael B. Feldman
co-chair, SIGAda Education Committee

Professor, Dept. of Electrical Engineering and Computer Science
School of Engineering and Applied Science
The George Washington University
Washington, DC 20052 USA
(202) 994-5253 (voice)
(202) 994-5296 (fax)
mfeldman@seas.gwu.edu (Internet)

"The most important thing is to be sincere, 
and once you've learned how to fake that, you've got it made." 
-- old show-business adage
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