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
X-Google-Thread: 103376,9f99a33281d5072c
X-Google-NewGroupId: yes
X-Google-Attributes: gida07f3367d7,domainid0,public,usenet
X-Google-Language: ENGLISH,ASCII
Path: 
 g2news1.google.com!news3.google.com!feeder2.cambriumusenet.nl!feed.tweaknews.nl!193.201.147.85.MISMATCH!border-2.ams.xsnews.nl!feed.xsnews.nl!border-4.ams.xsnews.nl!193.141.40.65.MISMATCH!npeer.de.kpn-eurorings.net!npeer-ng0.de.kpn-eurorings.net!newsfeed.arcor.de!newsspool2.arcor-online.net!news.arcor.de.POSTED!not-for-mail
From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: When a conditional expression is static, where can it be used?
Newsgroups: comp.lang.ada
User-Agent: 40tude_Dialog/2.0.15.1
MIME-Version: 1.0
Content-Type: text/plain; charset="iso-8859-1"
Content-Transfer-Encoding: 8bit
Reply-To: mailbox@dmitry-kazakov.de
Organization: cbb software GmbH
References: <4c2b1ecb$0$7670$9b4e6d93@newsspool1.arcor-online.net>
 <555e3a37-c709-4b9b-995a-907da862d4b7@m40g2000prc.googlegroups.com>
Date: Wed, 30 Jun 2010 19:35:38 +0200
Message-ID: <12ok8wnj6k4sw$.ravumwbhfb1h$.dlg@40tude.net>
NNTP-Posting-Date: 30 Jun 2010 19:35:36 CEST
NNTP-Posting-Host: 2737186b.newsspool4.arcor-online.net
X-Trace: 
 DXC=:=69l5M@@`1U`5g[@c]@J14IUK<Cl32<14Fo<]lROoR18kF<OcfhCO;d2NXIg1ES33[6LHn;2LCV>[<mhadbfdU;>^0SV3ak:F<88A`XR0O\l2
X-Complaints-To: usenet-abuse@arcor.de
Xref: g2news1.google.com comp.lang.ada:12046
Date: 2010-06-30T19:35:36+02:00
List-Id: <comp.lang.ada>

On Wed, 30 Jun 2010 07:39:24 -0700 (PDT), Adam Beneschan wrote:

> On Jun 30, 3:39�am, Georg Bauhaus <rm.dash-bauh...@futureapps.de>
> wrote:
>> A totally meaningless example just to illustrate
>> the question: �What is it that a compiler must report
>> for the case statement below, if anything?
> 
> The choice "Sa" is not covered by any alternative.  Other than that, I
> don't think there's anything wrong with the CASE statement, and if you
> had included a "when others =>" alternative I think it would be
> legal.  I'm not sure what potential problem you were trying to
> illustrate.

Let me propose this one instead: 

 � �type DOW is (Mo, Tu, We, Th, Fr, Sa, So);

 � �case D is
 � � � when (if D = Mo then Tu else Mo) => P;
 � � � when (if D = Tu then Tu else Mo) => Q;
 � � � when We..So => R;
 � �end case;

The above is equivalent to:

 � �case D is
 � � � when Tu => P;
 � � � when Mo => Q;
 � � � when We..So => R;
 � �end case;

But as Pascal suggested, it should not compile because D is not static. 

As for the problem Georg had in mid. Maybe it is this. Let you have some
function, say Gamma function. Now,

   x : constant := 0.1;
   Gx : constant := Gamma (1.1); -- Illegal, what a pity

Let us open the table of Gamma, scan it, and write something like:

   (if x < 0.0 then ... elsif x < 0.01 then ... )

This wonderful static function can then copied and pasted everywhere you
wanted to evaluate Gamma at compile time. Is it legal?

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de