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!feeder.eternal-september.org!gandalf.srv.welterde.de!news.jacob-sparre.dk!franka.jacob-sparre.dk!pnx.dk!.POSTED.rrsoftware.com!not-for-mail
From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Examining individual bytes of an integer
Date: Wed, 17 Oct 2018 17:10:13 -0500
Organization: JSA Research & Innovation
Message-ID: <pq8c06$85n$1@franka.jacob-sparre.dk>
References: <9d90fa3e-f800-4086-bf97-a65474a8140a@googlegroups.com>
 <pq0706$60k$1@dont-email.me> <g2hqooFq0usU1@mid.individual.net>
 <4ddbc9bf-0e2e-466d-8238-d8f709b985e1@googlegroups.com>
 <g2k5fbF9thnU1@mid.individual.net> <pq2sm7$in8$1@franka.jacob-sparre.dk>
 <35f53cd9-4979-49b8-a5df-2c1cf0764507@googlegroups.com>
 <pq5out$fu2$1@franka.jacob-sparre.dk> <pq6r7i$1o47$1@gioia.aioe.org>
Injection-Date: Wed, 17 Oct 2018 22:10:14 -0000 (UTC)
Injection-Info: franka.jacob-sparre.dk;
 posting-host="rrsoftware.com:24.196.82.226";
	logging-data="8375"; mail-complaints-to="news@jacob-sparre.dk"
X-Priority: 3
X-MSMail-Priority: Normal
X-Newsreader: Microsoft Outlook Express 6.00.2900.5931
X-RFC2646: Format=Flowed; Response
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.7246
Xref: reader02.eternal-september.org comp.lang.ada:54622
Date: 2018-10-17T17:10:13-05:00
List-Id: <comp.lang.ada>

"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message 
news:pq6r7i$1o47$1@gioia.aioe.org...
> On 2018-10-17 00:33, Randy Brukardt wrote:
>
>> That's the model for the entire compiler: all objects are
>> statically sized, and if needed, the actual data is found by indirection.
>
> That makes me missing RM rule (not advice): for any instance of
>
>    new X
>
> Allocate of the corresponding storage pool is called exactly once.

I would fight that at every level, since it would make a useful 
implementation of discriminated records impossible. Ada has always been very 
clear that non-contiguous representations are allowed.

It might make sense to introduce some sort of aspect to require a contigious 
representation for an array or record, so long as that's only required to be 
supported on sensible types.

In particular, this type should work with raising Storage_Error or some 
other exception on all Ada compilers:

     type Rec (D : Natural) is record
         Arr : String (1 .. D);
     end record;

     C0Rec : constant Rec(0) := (D => 0, Arr => "");
     C1Rec : constant Rec(1) := (D => 1, Arr => "R");
     A_Rec : Rec := C0Rec;

     A_Rec := C1Rec;
     A_Rec := (D => 3, Arr => "RLB");

A type like this pretty much requires discontiguous representations and 
reallocation on assignment.

                                          Randy.