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
	autolearn=unavailable autolearn_force=no version=3.4.4
Path: 
 eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!news.eternal-september.org!feeder.eternal-september.org!news.fcku.it!peer04.fr7!news.highwinds-media.com!fx39.am4.POSTED!not-for-mail
Subject: Re: Representation clause of a discriminated record
Newsgroups: comp.lang.ada
References: <677b076a-4cfb-4972-b5e5-d56c86e2179f@googlegroups.com>
 <nns21p$j1q$1@dont-email.me>
From: Per Sandberg <per.s.sandberg@bahnhof.se>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101
 Thunderbird/45.2.0
MIME-Version: 1.0
In-Reply-To: <nns21p$j1q$1@dont-email.me>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Message-ID: <n%noz.14277$OC.7713@fx39.am4>
X-Complaints-To: abuse@usenet.se
NNTP-Posting-Date: Wed, 03 Aug 2016 15:22:59 UTC
Organization: usenet.se
Date: Wed, 3 Aug 2016 17:22:59 +0200
X-Received-Bytes: 1661
X-Received-Body-CRC: 1653389907
Xref: news.eternal-september.org comp.lang.ada:31270
Date: 2016-08-03T17:22:59+02:00
List-Id: <comp.lang.ada>

Well
I would add a Aspect/Pragma "pack" as well, since some architectures 
may insert padding to start objects on boundaries /= 32 bit.

    type Discriminated_Record (Size : Natural) is
       record
          A : String (1 .. Size);
       end record with Pack => True;
    for Discriminated_Record use record
       Size at 0 range 0 .. 31;
    end record;
/Per

Den 2016-08-03 kl. 08:13, skrev Jeffrey R. Carter:
> On 08/02/2016 10:04 PM, David SAUVAGE wrote:
>>
>> What would be a valid representation clause for the following discriminated record ? (taken from the Ada wikibook [1])
>>
>>    type Discriminated_Record (Size : Natural) is
>>     record
>>        A : String (1 .. Size);
>>     end record;
>
> for Discriminated_Record use record
>    Size at 0 range 0 .. 31;
> end record;
>
> if Integer'Size = 32. You can't give a representation for A because you don't
> know it's size.
>