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From: bobduff@world.std.com (Robert A Duff)
Subject: Re: some questions re. Ada/GNAT from a C++/GCC user
Date: 1996/04/01
Message-ID: <Dp75z9.Jv8@world.std.com>#1/1
X-Deja-AN: 145272158
references: <wnewmanDoxrCp.DKv@netcom.com>
 <ROGOFF.96Mar28134118@sccm.Stanford.EDU> <4jhe1v$m0g@dayuc.dayton.saic.com>
 <4jp17p$17vn@watnews1.watson.ibm.com>
organization: The World Public Access UNIX, Brookline, MA
newsgroups: comp.lang.ada
Date: 1996-04-01T00:00:00+00:00
List-Id: <comp.lang.ada>

In article <4jp17p$17vn@watnews1.watson.ibm.com>,
Norman H. Cohen <ncohen@watson.ibm.com> wrote:
>Jean Ichbiah correctly saw the chaos that could result from approach (b).

I agree.

>He chose approach (c) for an exception occuring while the child task was
>still elaborating the declarative part of its task body and (a) for an
>exception occuring once the child task entered the sequence of statements
>of its task body.

IMHO, he should have chosen approach (c) for all exceptions.  A master
awaits its dependent tasks before continuing.  This would be the perfect
place to raise Tasking_Error if the dependent task(s) raise unhandled
exceptions.  Instead, the dependents silently disappear, like Ms. Rigby,
and then the parent task continues merrily on its way.

>...  (Anyone who has debugged a
>program in which a task raised an unhandled exception has quickly learned
>the value of adding a handler such as
>
>   when others =>
>      Display_Error_Message
>         ("Task of type XYZ abandoned due to unhandled exception.");
>
>to each task body.)

Yes.  Debugging these things is a nightmare, otherwise, because the
problem is not localized.

- Bob