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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: new revision ada
Date: 22 Jun 2004 21:26:40 +0100
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Brian May <bam@snoopy.apana.org.au> writes:

> If you want to try to recover from an error condition (as opposed to
> simply displaying/logging an error and failing) you often need to
> have detailed information on what was going on when the error
> occurred.
> 
> eg. ENGINE_FAILED(Number=>1, RPM=>xxxx,
> Occurred=>After_Switching_Fuel_Tanks) is a lot more informative then
> ENGINE_FAILURE and allows some sort of recovery process (eg. switch
> back to the previous fuel tank) instead of trying to guess
> information that was already known. (disclaimer: I haven't written
> such an application...)

This is fairly top-of-the-head stuff, but .. if you have an engine
management system, you had better design it to cope with engine
failure too. I just don't believe that a simple out-of-band thing like
an exception (even if decorated like this) can possibly provide a
mechanism for dealing with complex application-level handling of error
conditions.

If the engine fails while you're at the end of the runway, that's one
thing; if it fails mid-Atlantic that's quite another.

-- 
Simon Wright                               100% Ada, no bugs.