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From: Laurent.Guerby@enst-bretagne.fr (Laurent Guerby)
Subject: Re: Common Error/Exception Handler
Date: 1996/04/22
Message-ID: <4xzq84ypq6.fsf@leibniz.enst-bretagne.fr>#1/1
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sender: guerby@leibniz.enst-bretagne.fr
references: <4l8d5i$31g@news.sanders.lockheed.com> <Dq4p9v.Jv3@world.std.com>
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organization: Telecom Bretagne
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newsgroups: comp.lang.ada
Date: 1996-04-22T00:00:00+00:00
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John Cupak:
: Wouldn't it be possible with the Ada 95 exception mechanisms to create a
: package of standard exceptions and a common error message procedure,
: import/rename the exceptions where appropriate, and let the common error
: message procedure take care of the details? 

Robert A Duff wrote:
: I suppose it's possible, but it doesn't seem desirable.  The abstraction
: in question ought to define what sort of things are errors, and what
: exceptions are therefore raised.  Clients can then decide how to handle
: those errors.  Why do you think this information ought to be more
: global?

John Cupak wrote:
:I was thinking that a "global error/exception handler" package would be easier
: to maintain, since *all* error definitions and messages would be in a single
: place. 
: 
: Comments?

   I don't think  you (John) are  talking about exceptions in  general
(like Bob), but about exceptions that  get propagated to the main unit
and are "user" reported as a console message or in a log file.

   In this  last case, a global  mechanism is desirable and  simple to
implement in Ada 95 as a global  error reporting package using new Ada
(95) features in this area.

   You should have a look at RM95-A.13, and see that in Ada 95, all IO
exceptions are  defined in a   single package, Ada.IO_Exceptions,  and
renamed when needed   elsewhere ;-).  In Ada   95  a message  can   be
associated to an exception occurence, see RM95-11.4.1, Ada.Exceptions.
   
-- 
--  Laurent Guerby, student at Telecom Bretagne (France), Team Ada.
--  "Use the Source, Luke. The Source will be with you, always (GPL)."
--  http://www-eleves.enst-bretagne.fr/~guerby/ (GATO Project).
--  Try GNAT, the GNU Ada 95 compiler (ftp://cs.nyu.edu/pub/gnat).