From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,FREEMAIL_FROM
	autolearn=ham autolearn_force=no version=3.4.4
X-Google-Thread: 103376,86c750b8474bf6d5
X-Google-Attributes: gid103376,domainid0,public,usenet
X-Google-Language: ENGLISH,ASCII
Path: 
 g2news1.google.com!news1.google.com!news2.google.com!news.glorb.com!zen.net.uk!dedekind.zen.co.uk!peer.news.zetnet.net!peer-uk.news.demon.net!kibo.news.demon.net!news.demon.co.uk!demon!not-for-mail
From: Simon Wright <simon.j.wright@mac.com>
Newsgroups: comp.lang.ada
Subject: Re: About String
Date: Sat, 07 Jun 2008 17:18:12 +0100
Organization: Pushface
Message-ID: <m2od6d5id7.fsf@mac.com>
References: <g2bs6b$h2m$1@registered.motzarella.org>
NNTP-Posting-Host: pogner.demon.co.uk
Mime-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Transfer-Encoding: 8bit
X-Trace: news.demon.co.uk 1212855492 940 62.49.19.209 (7 Jun 2008 16:18:12
 GMT)
X-Complaints-To: abuse@demon.net
NNTP-Posting-Date: Sat, 7 Jun 2008 16:18:12 +0000 (UTC)
Cancel-Lock: sha1:Pm2f9T/7XUMTbNol8T95cao2Evg=
User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.2 (darwin)
Xref: g2news1.google.com comp.lang.ada:600
Date: 2008-06-07T17:18:12+01:00
List-Id: <comp.lang.ada>

S�bastien Morand <seb.morand@gmail.com> writes:

> So the main problem is error management. If one function raise
> exception, the exception can't be catch except with the following trick:

I don't know why you call it a trick! Perfectly standard Ada ...

> procedure Patati_Patata is
> begin
> 	declare
> 		s: String := A_Function_Raising_Constraint_Error;
> 	begin
> 		--  some code
> 		null;
> 	end;
> exception
> 	when Constraint_Error =>
> 		Put_Line("I got an error");
> end;
>
> Is there nicer way to do that? I'm trying to avoid Unbounded_String
> because of the conversion when mixing Unbounded_String and String.

You might want to handle the problem locally:

   procedure Patati_Patata is
   begin
      declare
         S : String := A_Function_Raising_Constraint_Error;
      begin
         --  some code
      exception
         when Constraint_Error =>
            --  deal with the problem and carry on ..
      end;
      --  .. here
   end Patati_Patata;

In general I don't like exception handlers which output a message and
then allow the procedure to look as though it has succeeded when in
fact something unforeseen has occurred, and is waiting to cause
mysterious problems much much later. Exceptions to this guideline
could include 'last-chance' exception handlers in tasks and the main
program; but if you are controlling missiles, medical equipment or
money it's probably better not to just stumble on in the hope that
things will turn out all right.