Re: Ariane 5 - not an exception?

[pmartin@alsys.com (Pascal Martin @lone)]

In article <4totv7$o9f@goanna.cs.rmit.edu.au>,
   rav@goanna.cs.rmit.edu.au (++           robin) writes:
>
> "Furthermore, he would have included a check that the value
> did not go out of range;"

This comment is totally misplaced: an Ada exception **is** a check.

Someone noted that shutdowning the system before it takes off was
probably a sound decision. Shutdown on board of a flying system looks
like the worst possible choice (could going **down** in a **flying**
system be a good choice, anyway ? :-).

I have seen systems which ignored suspect values, and send the latest
trusted result again and again instead, on the basis that the correct
result was probably close to this one. When you have nothing to work
with, this is perhaps the best gamble you can make. After all, rocket
science has a lot in common with gambling, looks like :-)

> "This project might well have been written in PL/I, which
> has excellent real-time facilities, including error
> handling, error simulation and validation facilities.
> The language has robust compilers, and experts with many
> years of PL/I programming experience.

Which PL/I compilers are available today on Sparc/Solaris, HP700/HPUX,
Windows/Intel and PowerPC/* ? I thought the language was dead since
the demise of IBM mainframes and the death of (the beloved) Multics.

I also though the PL/I experts have so many years of programming
experience that they are now.. retired.

PL/I had everything, except reserved words. The infamous "if if then then".

>"As to PL/I facilities, I refer to the SIGNAL statement,
>with which given conditions (errors such as fixed-point
>overflow) can be signalled as if the condition (error)
>actually occurred.

Sounds like the author never opened an Ada reference manual..

Pascal.