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=-0.3 required=5.0 tests=BAYES_00,
	REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4
Path: 
 eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!mx02.eternal-september.org!news.eternal-september.org!feeder.eternal-september.org!feeder.erje.net!eu.feeder.erje.net!news2.arglkargh.de!news.mixmin.net!aioe.org!.POSTED!not-for-mail
From: Pascal Obry <pascal@obry.net>
Newsgroups: comp.lang.ada
Subject: Re: type conversion
Date: Sun, 12 Oct 2014 11:37:18 +0200
Organization: Home - http://www.obry.net
Message-ID: <1413106638.3344.5.camel@obry.net>
References: <8d412a6d-5589-4601-a7f8-5bb6d1b8850f@googlegroups.com>
	 <FKl_v.358075$JH1.299775@fx08.iad>
	 <f14cdaa7-eff3-4ae6-bc5f-84079051ad14@googlegroups.com>
	 <kTn_v.410776$412.305487@fx30.iad>
Reply-To: pascal@obry.net
NNTP-Posting-Host: KpDErP2zF8NnM8mDMNH95w.user.speranza.aioe.org
Mime-Version: 1.0
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Complaints-To: abuse@aioe.org
X-Mailer: Evolution 3.12.6-1 
X-Notice: Filtered by postfilter v. 0.8.2
Xref: news.eternal-september.org comp.lang.ada:22380
Date: 2014-10-12T11:37:18+02:00
List-Id: <comp.lang.ada>

Le samedi 11 octobre 2014 =C3=A0 22:57 -0600, Shark8 a =C3=A9crit :=20
> Almost,
>=20
> Subtype Integer_String is new String
>    with Dynamic_Predicate =3D> Integer'Value( Integer_String ) in Integer
>                              or else raise Constraint_Error;


I don't see the point of the "or else" part. The exception
Assertion_Error will be raised if the first part "Interger'Value .. in
Integer" is not True anyway.

To control the message or the exception to be raised one can use the
Predicate_Failure aspect:

subtype Integer_String is new String
   with Dynamic_Predicate =3D> Integer'Value (Integer_String) in Integer,
        Predicate_Failure =3D> "not an integer string";

or

subtype Integer_String is new String
   with Dynamic_Predicate =3D> Integer'Value (Integer_String) in Integer,
        Predicate_Failure =3D>=20
          raise Constraint_Error with "not an integer string";

--=20
  Pascal Obry /  Magny Les Hameaux (78)

  The best way to travel is by means of imagination

  http://v2p.fr.eu.org
  http://www.obry.net

  gpg --keyserver keys.gnupg.net --recv-key F949BD3B