In article <5gm8a6$2qu$2@news.irisa.fr>, jezequel@irisa.fr (Jean-Marc
Jezequel) wrote:

> >I expect Meyers to push his own products, but to imply the Ariane-5 crash
> >was caused by poor choice of programming language seems out of step with
> >his otherwise impeccable manners.
> 
> Unless our English is so bad that it betrays our thinking, we 
> *never* implied such a thing. Just a point in a case: Eiffel simply did
not exist when they 
> worked on Ariane4. Let me quote the relevant section of the paper:
> 
> <<Is it the programming language's fault?
> Although one may criticize the Ada exception mechanism, it could have
been used here
>  to catch the exception. In fact, quoting the report: [omitted]
> In other words the potential problem of failed arithmetic conversions
was recognized.
>  Unfortunately, the fatal exception was among the three that were not
monitored,
>  not the four that were.>>
> 
> In case it is not clear enough, I repeat again: *it is not a language problem*
> Let me quote another part of the paper:
> <<Does this mean that the crash would automatically have been avoided
had the mission used
> a language and method supporting built-in assertions and Design by
Contract? >>
> 
> Please note the "language and method supporting built-in assertions and
Design by Contract"
> and please do not reduce it to : "a language". 

Let me quote the entire paragraph:

"Does this mean that the crash would automatically have been avoided had
the mission used a language and method supporting built-in assertions and
Design by Contract? Although it is always risky to draw such
after-the-fact conclusions, the answer is probably yes�"

And further:

"To attempt to reuse software without Eiffel-like assertions is to invite
failures of potentially disastrous consequences."

This is somewhat confusing, since assertions and design by contract can be
easily effected in Ada, the language used for Ariane5 (and in the other
languages disparaged in the article). I acknowledge that a strict reading
of the article would not prove my point, but the implication is obvious to
an unbiased reader, that the writer believes the use of Eiffel, as opposed
to "CORBA to C++ to Visual Basic to ActiveX to Java" and ofcourse Ada,
"probably" would have prevented the crash.

Don't get me wrong: I think Eiffel is a fine language.

My point was that assertions and design by contract are good, but are not
enforced by Eiffel any more than any other modern programming language.
The presence of "built-in" assertions does not mean they will be used; a
person who would use assertions fastidiously in Eiffel is probably already
using them in C++ or Ada. If your article does not seem slanted to you,
that is probably because you wrote it - I am not the only reader that
detected a pro-Eiffel bias.

Anders.

-- 
Anders Pytte            Milkweed Software
RR 1, Box 227           Voice: (802) 472-5142
Cabot VT 05647          Internet: milkweed@plainfield.bypass.com