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=-0.9 required=5.0 tests=BAYES_00,FORGED_GMAIL_RCVD,
	FREEMAIL_FROM autolearn=no autolearn_force=no version=3.4.4
X-Google-Thread: 103376,5f5a48f21d7f7525
X-Google-NewGroupId: yes
X-Google-Attributes: gida07f3367d7,domainid0,public,usenet
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news1.google.com!news3.google.com!feeder.news-service.com!85.214.198.2.MISMATCH!eternal-september.org!.POSTED!not-for-mail
From: Warren <ve3wwg@gmail.com>
Newsgroups: comp.lang.ada
Subject: Re: Inferring array index type from array object
Date: Mon, 28 Jun 2010 13:44:22 +0000 (UTC)
Organization: A noiseless patient Spider
Message-ID: <Xns9DA563139F62CWarrensBlatherings@85.214.73.210>
References: 
 <6b20ed09-efc1-4df7-90f9-5e141482e8d0@d37g2000yqm.googlegroups.com>
 <1305oqccr1h2t$.x33x4oxwd84d$.dlg@40tude.net>
 <88ec2vF3uqU1@mid.individual.net>
 <Xns9DA07FC9F98B5WarrensBlatherings@81.169.183.62>
 <88f9osFmcmU1@mid.individual.net>
Injection-Date: Mon, 28 Jun 2010 13:44:22 +0000 (UTC)
Injection-Info: mx03.eternal-september.org;
 posting-host="qtwthkrgwQVPvJFfslJIDQ";
	logging-data="9609"; mail-complaints-to="abuse@eternal-september.org";
	posting-account="U2FsdGVkX18jGtDVImxHWpYRrUdcBZ9yRNLqnMLwWhg="
User-Agent: Xnews/5.04.25
X-Face: 
 &6@]C2>ZS=NM|HE-^zWuryN#Z/2_.s9E|G&~DRi|sav9{E}XQJb*\_>=a5"q]\%A;5}LKP][1mA{gZ,Q!j
Cancel-Lock: sha1:z1nOtS6JcYqUZaoAbjttRAH/01w=
Xref: g2news1.google.com comp.lang.ada:11966
Date: 2010-06-28T13:44:22+00:00
List-Id: <comp.lang.ada>

Niklas Holsti expounded in news:88f9osFmcmU1@mid.individual.net:

> Warren wrote:
>> Niklas Holsti expounded in news:88ec2vF3uqU1@mid.individual.net:
>>> Dmitry A. Kazakov wrote:
>>>> On Wed, 23 Jun 2010 00:30:23 -0700 (PDT), Maciej Sobczak wrote:
>> ..
>>>>> 2. Is it possible to declare the index variable without hardcoding
>>>>> the index type (that is, to infer it from the array object)?
>>>> No, without improving the type system. E.g. introducing abstract
>>>> index types, and abstract range types (or more general sets of index
>>>> types), and abstract composite types like arrays.
>>> I don't think such large language changes would be necessary. The 
>>> expression S'Range gives the compiler all the information about the
>>> type and its constraints, so I see no reason why Ada could not be
>>> extended simply to allow S'Range in a variable declaration, as in the
>>> above quoted "I : S'Range". The declared variable "I" would have the
>>> same (sub)type as the loop counter in "for I in S'Range loop ...".
>> 
>> I think most would agree that this is a "convenience" feature.
> 
> Yes, but in other contexts, when we advocate Ada, we often make a big 
> point of the "convenience" of the 'Range attribute for arrays, such as 
> "No need to pass extra parameters for array index bounds, just use 
> 'Range". The suggestion to let variables be declared by the "type" 
> S'Range (or, if desired, a new attribute S'Index_Type) has a similar 
> advantage (but a weaker one, I admit).

But how far down that road do you want to go? This is
the crux of the issue. 

I'd find ++X or X += n convenient. But should that be 
implemented in Ada?  I'm ok with leaving it out.

At some point, you have to draw a line in the sand.

Warren