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From: Florian Weimer <fw@deneb.cygnus.argh.org>
Subject: Re: Help Me Please :)
Date: 2000/03/20
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Newsgroups: comp.lang.ada
Date: 2000-03-20T07:09:32+00:00
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Robert A Duff <bobduff@world.std.com> writes:

> Richard D Riehle <laoXhai@ix.netcom.com> writes:
> 
> > In some languages, exceptions are first class objects.  Ada exceptions are
> > not first class objects for very good reasons.
>                               ^^^^^^^^^^^^^^^^^
> 
> I beg to differ.  I think this is one of the few cases where those other
> languages got it right, and Ada got it wrong.

Yes, that's my impression as well.  Although the Ada approach makes
it much easier to write general purpose exception handlers (which only
log unexpected exceptions), some things are quite difficult to handle.

For example, look at the POSIX.5 binding.  There's a single POSIX_Error
exception and a task-specific variable to tell one kind of error
from the other.  The other possibility would have been to use one
exception per error, but this would make exception handlers very
elaborated (they would have to handle quite a lot of them).  I wish I
could create a hierarchy of exceptions in Ada (so that, for example,
handling POSIX_Error catches Broken_Pipe_Error, too)...