Re: Ada and Automotive Industry

[Chris Hills <chris@phaedsys.demon.co.uk>]

In article <Pine.GSO.3.95.961129151026.24389C-100000@nunic.nu.edu>,
Richard Riehle <rriehle@nunic.nu.edu> writes
>On 27 Nov 1996, Robert Dewar wrote:
>
> 
>  Now, for the Ada plug. I know of at least one software developer that
>  is re-engineering their 8051-based product to a different processor,
>  one that supports Ada, with plans to use Ada as its development
>  language on that new processor -- for safety reasons.  And this is
>  a commercial developer with no, underscore NO, connection to the
>  Department of Defense.

I am ammussed by the comment "for saftey reasons" ADA is no safer than
any other language. It is only safer in theroy. It depends on the
standard of the compilers and tools etc. 

I believe that at the current time there are nearly 2000 requests for
clarification on the ADA standard. This is 2000 places where
implimentors of tools are not sure what the standard means or have
dissagreed over implimentation. Therefore no two ADA compilers are
guaranteed to produce the same output.

I was once told to use Modula 2 because it was "safe" It turned out that
the compiler suite had been written in Intel assembler (supposedly a
very unsafe language) and was full of bugs! In the end we used a Borland
C compiler as there were more tools available to check the code and (due
to sheer weight of users in the world) we were failry certain we knew of
all the problems (bugs) with the compiler. We could not find another
(successful) user of the Mod2 compiler we had much less one who had
exercised it to the level we intended to use it.

So no matter how *theoretically* safe a language is supposed to be in
practice it is irrelevant if it is not practically safe. C can be a very
safe language if one uses a good tool set in a sensible manner.
Incorrect use of any language will cause problems. It was Ada on the
Ariane 5 rocket that crashed in the summer. Not directly the fault of
Ada but as I under stand it.  It was partly because some one had
deliberatly got round the strict ADA type checking. 

Yes ADA is theoretically strongly typed but if, to use it for real work,
one must dissable this it makes it no better than C. Actually it is
worse because peolpe have this false sence of security that if it
copmpiles in ADA it must be safe....

The question is not is it a Theoretically safe language but is thew
implimentation of the language accurate and it the tool set good, it's
user understood and above all correctly used.


NB: I am using C in an area more important than just "safty critical"
money is involved.... What a world we live in :-(


Regards

        Chris

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