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: 103376,703c4f68db81387d
X-Google-Thread: 109fba,703c4f68db81387d
X-Google-Thread: 115aec,703c4f68db81387d
X-Google-Thread: f43e6,703c4f68db81387d
X-Google-Attributes: gid103376,gid109fba,gid115aec,gidf43e6,public
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news1.google.com!news3.google.com!news.glorb.com!fr.ip.ndsoftware.net!nerim.net!oleane.net!oleane!not-for-mail
From: =?ISO-8859-1?Q?Falk_Tannh=E4user?= <falk.tannhauser@crf.canon.fr>
Newsgroups: comp.lang.ada,comp.lang.c++,comp.realtime,comp.software-eng
Subject: Re: Teaching new tricks to an old dog (C++ -->Ada)
Date: Wed, 09 Mar 2005 15:24:57 +0100
Organization: Canon Research Centre France
Message-ID: <d0n0vg$4oa$1@s1.news.oleane.net>
References: <4229bad9$0$1019$afc38c87@news.optusnet.com.au>
 <1110032222.447846.167060@g14g2000cwa.googlegroups.com>
 <871xau9nlh.fsf@insalien.org>
 <3SjWd.103128$Vf.3969241@news000.worldonline.dk>
 <87r7iu85lf.fsf@insalien.org> <1110052142.832650@athnrd02>
 <d0dkq6$781$1@titan.btinternet.com>
 <1110284070.410136.205090@o13g2000cwo.googlegroups.com>
 <395uqaF5rhu2mU1@individual.net> <uk6oigfzi.fsf@obry.org>
 <1110329098.642196@athnrd02> <u3bv5gq0y.fsf@obry.org>
 <1110361741.551255@athnrd02>
 <422edaec$0$26554$9b4e6d93@newsread4.arcor-online.net>
NNTP-Posting-Host: centre.crf.canon.fr
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Transfer-Encoding: 7bit
X-Trace: s1.news.oleane.net 1110378288 4874 194.2.158.33 (9 Mar 2005 14:24:48
 GMT)
X-Complaints-To: abuse@oleane.net
NNTP-Posting-Date: Wed, 9 Mar 2005 14:24:48 +0000 (UTC)
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US;
 rv:1.7.5) Gecko/20041217
X-Accept-Language: de, fr, pl, en, en-us
In-Reply-To: <422edaec$0$26554$9b4e6d93@newsread4.arcor-online.net>
Xref: g2news1.google.com comp.lang.ada:8930 comp.lang.c++:44764
 comp.realtime:1122 comp.software-eng:4681
Date: 2005-03-09T15:24:57+01:00
List-Id: <comp.lang.ada>

Georg Bauhaus wrote:
> Ioannis Vranos wrote:
>> Pascal Obry wrote:
>>>    for K in Data'Range loop
>>>       ... Data(k)...
>>>
>> ISO C++ speaking, one may use vector::at() which provides boundary 
>> checking, however the aforementioned way is *always* 100% safe
> 
> The loop happens to be "safe" but not by the scope and range
> of i. The loops aren't equivalent, strictly speaking, because
> the loop counter doesn't act as a constant.
> Disciplined use of iterators/pointers/indices is not the same
> thing as a constant loop index:
> 
>  for (vector<int>::size_type i=0; i<Data.size(); ++i) {
>    if (Data.at(i)== 1)      i = 100;
>  }
> 
> This text is compiled without complaint as should be, because it _might_
> have been the programmer's intention to set the index to some value off
> bounds, and he/she _might_ not have wanted a while loop instead of a for
> loop.
> 
> Some languages provide language facilities to express this difference.
> A constant loop index can make some proofs easier.

Perhaps the closest way you can get to this in C++ is

   std::vector<foo_type> Data;
...
   std::for_each(Data.begin(), Data.end(), DoSomething);

where "DoSomething" evaluates to a so-called "function object"
having an "operator()" accepting a (reference to) "foo_type".

Such function objects can be of dedicated classes, or can be constructed
"on the fly" (even it the latter possibility is sometimes a bit awkward
due to the lack of closures / lambda expressions in the language - btw,
does Ada have something like that?).

Falk