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=ham
	autolearn_force=no version=3.4.4
X-Google-Thread: 103376,f7c38a023cf370dc
X-Google-NewGroupId: yes
X-Google-Attributes: gida07f3367d7,domainid0,public,usenet
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news2.google.com!news3.google.com!proxad.net!feeder1-2.proxad.net!news-transit.tcx.org.uk!feeder.news-service.com!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
Date: Thu, 21 Jul 2011 11:43:22 +0200
From: Georg Bauhaus <rm.dash-bauhaus@futureapps.de>
User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US;
 rv:1.9.2.18) Gecko/20110616 Thunderbird/3.1.11
MIME-Version: 1.0
Newsgroups: comp.lang.ada
Subject: Re: Should representation clauses be complete for each bit?
References: 
 <73c10395-ec4f-4a02-b0fc-e35bc14424fa@e18g2000vbx.googlegroups.com>
 <wcczkk9ngxy.fsf@shell01.TheWorld.com>
 <4e26f324$0$6549$9b4e6d93@newsspool4.arcor-online.net>
 <wccsjq0vp2h.fsf@shell01.TheWorld.com>
 <b3cb81ff-3e7f-4ff2-aa83-fa7de9814eab@dp9g2000vbb.googlegroups.com>
In-Reply-To: 
 <b3cb81ff-3e7f-4ff2-aa83-fa7de9814eab@dp9g2000vbb.googlegroups.com>
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Message-ID: <4e27f4ba$0$6584$9b4e6d93@newsspool3.arcor-online.net>
Organization: Arcor
NNTP-Posting-Date: 21 Jul 2011 11:43:23 CEST
NNTP-Posting-Host: e6f7e5a3.newsspool3.arcor-online.net
X-Trace: 
 DXC=:]RJWV6BZmdf1oJaJ0@dmgMcF=Q^Z^V3h4Fo<]lROoRa8kF<OcfhCOk3YJi2hk2k\anc\616M64>jLh>_cHTX3jmUn0WnTYPCFe
X-Complaints-To: usenet-abuse@arcor.de
Xref: g2news2.google.com comp.lang.ada:21233
Date: 2011-07-21T11:43:23+02:00
List-Id: <comp.lang.ada>

On 21.07.11 09:37, Martin wrote:
> On Jul 20, 6:28 pm, Robert A Duff <bobd...@shell01.TheWorld.com>
> wrote:
>> Georg Bauhaus <rm.dash-bauh...@futureapps.de> writes:
>>> On 20.07.11 16:51, Robert A Duff wrote:
>>
>>>> By the way, I find Ada's representation clauses to be at the wrong
>>>> level of abstraction.  Why can't I just write a single line of code
>>>> that means "put all the components in declaration order with no gaps
>>>> in between"?
>>
>>> Is this a frequent use case?
>>
>> Yes, I think so.
>>
>> - Bob
> 
> I think you're right, Bob. In fact, I'd go so far as to say it's very,
> very common.
> -- Martin

More specifically, if the original example of "not all bits used and some
gaps between them" is unusual, is it so

- when mapping to a set of hardware pins, say?

- or when "interfacing" to C structs?

For C structs, declaration order seems very convenient, as C keeps
declaration order.  But C may well introduce gaps between structure
components whenever its alignment rules requires.  Then I will want
gaps in Ada, too.  Is a convention pragma sufficient, then?