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From: Robert Dewar <robert_dewar@my-deja.com>
Subject: Re: Ada and Java. different behaviour. casting long to int problem.
Date: 1999/06/22
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In article <3766C842.E1EAB60A@pwfl.com>,
  diespammer@pwfl.com wrote:

> The people burnt to a crisp in the crash of an
> airplane aren't going to care that "The Programmer Should Have
> Read The
> Standard Better." Dead is just as dead if it was the compiler
> that was
> at fault. What the programmer *should* do is mostly
> irrelevant. What the
> programmer is *likely* to do is go with all of his years of
> grade school
> arithmetic and casually believe that X := X + 1 will yield the
> expected result.

This is unrealistic. The idea that safety critical software
depends on programmers doing the right thing on the basis of
"casual belief" is way off the mark.

In fact an unanticipated overflow causing an exception may be
as dangerous, if not MORE dangerous than an ignored overflow
(Ariane 5 was a nice demonstration of this).

In practice in safety critical software, formal verification
and certification techniques are used to ensure that NEITHER
event happens.

Don't worry, when you fly on a plane, regardless of the language
used, you are not at the mercy of programmers doing *anything*
casually. Safety critical software just does not work this way!


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