Royal Pain

[Henry Spencer]

On Thu, 17 Jun 2004, Lennart Sorensen wrote:
> Well I am certainly happy that not all companies (and programmers) think
> perfection is a waste of time.  Companies that work on automation
> software for trains and subways, and software for air planes and such
> certainly live by a much higher standard (and should too)...

You're confusing perfection with safety.  The latter does not require the
former; indeed, there is quite a body of literature now on how to do a
good job on safety-critical software, and nowhere in it will you find a
claim that it's equivalent to bug-free software.  *Certain classes* of
bugs must be firmly precluded, but others need not be, and the finite
effort available should be focused first on the things that really matter. 
Keeping the software's behavior within bounds is far more important than
making it exactly right.  Moreover, safety-critical software has to do a
number of things that are just outside the scope of bug-free software,
like making a real effort to cope adequately with very unlikely (or even
"can't happen") external conditions.

                                                          Henry Spencer
                                                       henry-lqW1N6Cllo0sV2N9l4h3zg at public.gmane.org

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