Re: Ada and Automotive Industry

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

In article <dewar.849497905@merv>, Robert Dewar <dewar@merv.cs.nyu.edu>
writes
>Chris says
>
>"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.
>"
>
>Well you can be amused at anything you like, but in this case you are
>being amused at your own ignorance.

I am not surprised by this reply and the following:

>Chris says
>>"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."
>And in that quote you show you do not understand AT ALL the concept of
>safety in the design of a language. It has nothing whatsoever with how
>buggy or unbuggy compilers or other tools might be!

and:

> c) this also includes questions about the language whose answer should
>     be clear to anyone who understands the language. No one can
>guarantee that everyone understands what they should, but all questions
>get logged, even silly ones.


One only has to look at the header: merv.cs.nyu.edu an educationalist
who designs languages? An Ivory Tower on and Ivory Tower?

As I said several times it does not matter how THEORETICALLY safe a
language is  if the implimentation and the supporting tools are bug
ridden it is of little use to anyone.

I could depend on the REAL (as in it had a customer and HAD TO WORK in a
real environment)  program written in C but we could not depend on the
same program in Mod2 because the develpoment system was bug ridden. In
other words the Mod2 program would not perform as the language dictated
and the program was unsafe.

Your Item "c" shows aragance beyond belife. "whose answer should be
clear to anyone who understands the language".  Obviously the
description specification was not clear. If any *one* person can make
the mistake so can another, meaning that in implimentation the result
may not be the same. OR do you mean that any one who does not understand
the language the same way you do? When is a silly bug a safe one?
 
I may not understand "AT ALL the concept of saftey in the design of a
language" but my sw has to run and work without error day in day out.
(My current Sw when finished is expected to run for 15 years from switch
on (24 hours a day) with down time of 15 min a year for planned
upgrades). The last system I did (also in C) has run for 2 years without
problems. 

The Ariane 5 rocket had Ada Sw (a "Safe" language) and crashed after 39
seconds (a bit of a red herring as Ada was not directly to blame and the
same could have been done in C or Mod2) SO what is the excuse here? the
Sw team did not understand the use of the language? If it is that hard
to use and that easy to miss use it is unsafe in practice.

As I repeatedly say the theory is fine (it's what accademics are good at
:-) but is it safe in practice?

BTW your arguments would look better without personal abuse and trying
to sound superior

>but in this case you are being amused at your own ignorance.
>whose answer should  be clear to anyone who understands the language


You have no idea who you are arguing with.

Regards

        Chris


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