Re: Trust but verify (was Re: Papers on the Ariane-5 crash and Design by Contract

[Robb Nebbe <nebbe@iam.unibe.ch>]

Bertrand Meyer wrote:
> 
> Robert S. White wrote:
> 
> > So don't think it is just him that has been put off by people
> > saying that "Design By Contract with the Eiffel language"
> > would have (alone - without simulation or HWIL) testing)
> > prevented the [Ariane] 5 disaster.
> 
> In this particular case there is good reason to think that good
> use of Design by Contract would in fact have evidenced the bug
> early in the development cycle, long before any simulation or
> testing.

The problem is that you conclusion is based on a misunderstanding
of what actually happened. Your mistakes are relatively clear to
anyone who knows Ada. Obviously, you don't see any problem with the
paper or its conclusions because you don't know Ada well enough
to interpret the findings of the Ariane 5 report. 

 
> It's been amazing in this discussion how some postings have taken
> to task our paper for ideas that are not there.
> The points that it makes are pretty simple, and there for everyone
> to examine (http://www.eiffel.com, link to "Ariane 5 paper");
> after reading most of the discussion, and re-reading the paper,
> I think that its arguments and conclusion are perfectly in line with
> many useful comments made by people who thought they disagreed with it.
> Please check what it really has to say.

The problem is that there are a number of factual errors linked to
you lack of knowledge of Ada. If everything you said was true then
you conclusions would also be true. Just because someone, out of
ignorance, claims something is true does not make it so. 


> 
> --
> Bertrand Meyer, President, ISE Inc., Santa Barbara (California)
> 805-685-1006, fax 805-685-6869, <Bertrand.Meyer@eiffel.com> -
> ftp://ftp.eiffel.com
> Visit our Web page: http://www.eiffel.com
>         (including instructions to download Eiffel 4 for Windows)

Robb Nebbe