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=-2.9 required=5.0 tests=BAYES_00,MAILING_LIST_MULTI
	autolearn=unavailable autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,715875e575230543
X-Google-Attributes: gid103376,public
X-Google-ArrivalTime: 2003-10-21 23:59:44 PST
Path: 
 archiver1.google.com!news2.google.com!news.maxwell.syr.edu!skynet.be!skynet.be!freenix!enst.fr!melchior!cuivre.fr.eu.org!melchior.frmug.org!not-for-mail
From: christoph.grein@eurocopter.com
Newsgroups: comp.lang.ada
Subject: Re: Thought this was funny
Date: Wed, 22 Oct 2003 08:44:44 +0200 (MET DST)
Organization: Cuivre, Argent, Or
Message-ID: <mailman.164.1066805910.25614.comp.lang.ada@ada-france.org>
Reply-To: grein@egypt.otn.eurocopter.de
NNTP-Posting-Host: lovelace.ada-france.org
Mime-Version: 1.0
Content-Type: TEXT/plain; charset=us-ascii
X-Trace: melchior.cuivre.fr.eu.org 1066805910 55970 80.67.180.195 (22 Oct 2003
 06:58:30 GMT)
X-Complaints-To: usenet@melchior.cuivre.fr.eu.org
NNTP-Posting-Date: Wed, 22 Oct 2003 06:58:30 +0000 (UTC)
To: comp.lang.ada@ada-france.org
Return-Path: <christoph.grein@eurocopter.com>
X-Authentication-Warning: mail.eurocopter.com: uucp set sender to
	<christoph.grein@eurocopter.com> using -f
Content-MD5: y14Ww4VSJH89/tfQRdNxoA==
X-Mailer: dtmail 1.2.1 CDE Version 1.2.1 SunOS 5.6 sun4u sparc 
X-Virus-Scanned: by amavisd-new-20030616-p5 (Debian) at ada-france.org
X-BeenThere: comp.lang.ada@ada-france.org
X-Mailman-Version: 2.1.2
Precedence: list
List-Id: Gateway to the comp.lang.ada Usenet newsgroup
	<comp.lang.ada.ada-france.org>
List-Unsubscribe: <http://www.ada-france.org/mailman/listinfo/comp.lang.ada>,
	<mailto:comp.lang.ada-request@ada-france.org?subject=unsubscribe>
List-Post: <mailto:comp.lang.ada@ada-france.org>
List-Help: <mailto:comp.lang.ada-request@ada-france.org?subject=help>
List-Subscribe: <http://www.ada-france.org/mailman/listinfo/comp.lang.ada>,
	<mailto:comp.lang.ada-request@ada-france.org?subject=subscribe>
Xref: archiver1.google.com comp.lang.ada:1372
Date: 2003-10-22T08:44:44+02:00

> case <boolean expression> is
>   when true =>
>        <do something>
>
>   when false =>
>        <do something else>
>
> end case;

What's so funny about this code. I also normally use if-statements with booleans but 
there are circumstances where a case statement seems more appropriate to the 
problem at hand.

Take e.g. kind of double-buffering. I use an array indexed by Boolean and switch 
via
  "X := not X;"

In such cases, neither True nor False denote something which is wrong or right, 
so I prefer the case statement.

Switching with a two-valued enumeration is not so elegant, you need a switch 
table or a case statement instead of the simple "X := not X;".

[Ducking away because this is an abstraction inversion :-]