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: 103376,7b6305d0d57a9f34
X-Google-NewGroupId: yes
X-Google-Attributes: gida07f3367d7,domainid0,public,usenet
X-Google-Language: ENGLISH,ASCII-7-bit
Received: by 10.68.19.161 with SMTP id g1mr5543419pbe.7.1319879143564;
        Sat, 29 Oct 2011 02:05:43 -0700 (PDT)
Path: 
 p6ni21469pbn.0!nntp.google.com!news1.google.com!goblin2!goblin.stu.neva.ru!feeder.erje.net!eternal-september.org!feeder.eternal-september.org!.POSTED!not-for-mail
From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Normalizing array indices
Date: Sat, 29 Oct 2011 10:05:42 +0100
Organization: A noiseless patient Spider
Message-ID: <m2mxckp3q1.fsf@pushface.org>
References: <Pine.LNX.4.64.1110282013540.21821@medsec1.medien.uni-weimar.de>
Mime-Version: 1.0
Injection-Info: mx04.eternal-september.org;
 posting-host="dFCm8HWntFqmDIilBLqEJQ";
	logging-data="4537"; mail-complaints-to="abuse@eternal-september.org";
	posting-account="U2FsdGVkX1/7mUjs6qamcw4e2xA5hghVQdii5lnMH8I="
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.3 (darwin)
Cancel-Lock: sha1:lFsDA6JSQvbnDyeMx0iQgreR10g=
	sha1:xIl+KEWY/86wmouUKPXHZKbpcCE=
Xref: news1.google.com comp.lang.ada:18743
Content-Type: text/plain; charset=us-ascii
Date: 2011-10-29T10:05:42+01:00
List-Id: <comp.lang.ada>

Stefan.Lucks@uni-weimar.de writes:

> In many cases, array ranges starting with an arbitrary index are
> better (higher level) to model an application's demands. But
> sometimes, like when applying a sorting routine, this extra
> information is actually some ballast.
>
> Ideally, the specification of a subprogram would carry the information 
> that the subprogram only uses "normalized" array indices, to free the 
> tester from having to consider test cases with different A'First:
>
>   procedure Sort(A: in out Sort_Array_Type(1 .. <>)); 
>
> The user can still call Sort with any array of range, say, 4711 .. 9421, 
> but Sort coldn't tell that apart from an array of range 1 .. 4711. Thus, 
> there is no reason for additional test cases with different values 
> for A'First. 

But your problem was with A'Last, surely?

I've had more surprises with

   type Arr is array (Integer range <>) of Float;
   A : Arr := (1.0, 2.0, 3.0);

where A'First is Integer'First (on GNAT), ie -2**31.