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: a07f3367d7,aaabba5db6b5df34
X-Google-Attributes: gida07f3367d7,public,usenet
X-Google-NewGroupId: yes
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news2.google.com!news4.google.com!feeder.news-service.com!news2.euro.net!82.197.223.106.MISMATCH!feeder1.cambriumusenet.nl!feed.tweaknews.nl!192.87.166.28.MISMATCH!tudelft.nl!txtfeed1.tudelft.nl!feed.xsnews.nl!border-1.ams.xsnews.nl!151.189.20.20.MISMATCH!newsfeed.arcor.de!newsspool1.arcor-online.net!news.arcor.de.POSTED!not-for-mail
From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Min/Max attribute makes promises it can't keep
Newsgroups: comp.lang.ada
User-Agent: 40tude_Dialog/2.0.15.1
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Reply-To: mailbox@dmitry-kazakov.de
Organization: cbb software GmbH
References: 
 <98b7e6f2-32ed-465c-9a52-541b7878ca86@y17g2000yqd.googlegroups.com>
  <9b17e781-f46a-4384-8809-b16602d10114@y30g2000yqh.googlegroups.com>
 <wcczl0o7g13.fsf@shell01.TheWorld.com>
 <880dc0f0-7fff-440d-8aad-6ce745fcfed8@h27g2000yqm.googlegroups.com>
 <246a7cec-bd5f-4c48-a6cb-3874080c19ab@y17g2000yqd.googlegroups.com>
 <591866ec-fa46-440c-b6fc-3092985ae3df@r27g2000yqn.googlegroups.com>
 <8ab2d2d1-b7dc-47bf-824f-4cab334a3fd6@11g2000yqr.googlegroups.com>
 <1pbp1hhh5yb9k.b6b9xs33b4od$.dlg@40tude.net>
 <4bd841e7$0$7658$9b4e6d93@newsspool1.arcor-online.net>
 <1t4extnm6iluj.r4x652cntogc$.dlg@40tude.net> <hra82e$i18$1@munin.nbi.dk>
 <1p28brlj9yc3k$.1nv0ey1aadvoi$.dlg@40tude.net> <hrgf10$qvv$1@munin.nbi.dk>
Date: Sat, 1 May 2010 08:28:10 +0200
Message-ID: <rypl0nzasa10$.1drivrnhe5u64$.dlg@40tude.net>
NNTP-Posting-Date: 01 May 2010 08:28:11 CEST
NNTP-Posting-Host: 91c8f2ab.newsspool3.arcor-online.net
X-Trace: 
 DXC=_goQVIh[GEefF8a^:6>b7eMcF=Q^Z^V3h4Fo<]lROoRa8kF<OcfhCOkc>T\^nE^;mi[6LHn;2LCVn[<mhadbfdUkUTmhC]PEPNaTn><CFAEb9m
X-Complaints-To: usenet-abuse@arcor.de
Xref: g2news2.google.com comp.lang.ada:11267
Date: 2010-05-01T08:28:11+02:00
List-Id: <comp.lang.ada>

On Sat, 1 May 2010 00:42:53 -0500, Randy Brukardt wrote:

> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message 
> news:1p28brlj9yc3k$.1nv0ey1aadvoi$.dlg@40tude.net...
>> On Wed, 28 Apr 2010 16:07:24 -0500, Randy Brukardt wrote:
>>
>>> As for the initial concern about giving a subtype name, in the case of
>>> literals you have to give one somewhere (since a literal can be of many
>>> different types, and the results can vary depending on the type used --  
>>> not
>>> for 'Length, but for 'Last and most other properties).
>>
>> No problem, Ada supports overloading in the result type. E.g. abs (-1) is
>> OK.
> 
> That doesn't help. Consider:
> 
>     type My_String is array (Natural range <>) of Character;
> 
> Now, if you wrote:
> 
>     "ABC"'First
> 
> The answer depends on whether the type of the prefix is String or My_String, 
> but the type is Integer'Base in both cases. No amount of overloading will 
> help.

How is that different to:

   package P is
      function ABC return String;
   end P;
   package Q is
      type My_String is array (Natural range <>) of Character;
      function ABC return My_String;
   end Q;
   use P,Q;
   ...
   ABC'First; -- Ambiguous

> The language does not want the compiler to have to list out all of the 
> possible types for a string literal, figure out the appropriate bounds for 
> all of them, take all of the ones with the appropriate index type, and then 
> allow the attribute if the answer is the same.

That would be silly, of course. But it is not what I meant. Attribute
should be an overloaded operation as any other. If the expression happens
to be ambiguous there are language means to specify what it is.

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