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=-0.3 required=5.0 tests=BAYES_00,
	REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4
X-Google-Thread: 103376,147f221051e5a63d
X-Google-Attributes: gid103376,domainid0,public,usenet
X-Google-Language: ENGLISH,ASCII
Path: 
 g2news1.google.com!news1.google.com!border1.nntp.dca.giganews.com!nntp.giganews.com!newsfeed00.sul.t-online.de!t-online.de!news.karotte.org!news.musoftware.de!wum.musoftware.de!feeder.erje.net!newsfeed-fusi2.netcologne.de!news.netcologne.de!newsfeed-hp2.netcologne.de!newsfeed.arcor.de!newsspool1.arcor-online.net!news.arcor.de.POSTED!not-for-mail
Date: Sat, 17 May 2008 18:18:32 +0200
From: Georg Bauhaus <see.reply.to@maps.futureapps.de>
Reply-To: rm.tsho+bauhaus@maps.futureapps.de
User-Agent: Thunderbird 2.0.0.14 (X11/20080502)
MIME-Version: 1.0
Newsgroups: comp.lang.ada
Subject: Re: memory management in Ada: tedious without GC?
References: 
 <4ddef8bf-b5b1-4d7e-b75b-386cd6c8402c@l17g2000pri.googlegroups.com>
 <482E8A9D.5040401@obry.net> <8ACXj.3769$IK5.622@trnddc04>
 <482EF951.9010604@obry.net>
In-Reply-To: <482EF951.9010604@obry.net>
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 8bit
Message-ID: <482f0558$0$6518$9b4e6d93@newsspool4.arcor-online.net>
Organization: Arcor
NNTP-Posting-Date: 17 May 2008 18:18:32 CEST
NNTP-Posting-Host: 41e22630.newsspool4.arcor-online.net
X-Trace: 
 DXC=>C3oKA1VHZ3RLigj];iP=84IUK<Cl32<14Fo<]lROoR18kF<OcfhCO;RXf;QenT\C=PCY\c7>ejV8Lg5Ug[ai948lB=geBTVCj9
X-Complaints-To: usenet-abuse@arcor.de
Xref: g2news1.google.com comp.lang.ada:161
Date: 2008-05-17T18:18:32+02:00
List-Id: <comp.lang.ada>

Pascal Obry wrote:
> Bob Klungle a �crit :

>> Actually, the same construct exists in c/c++.
> 
> Ok, I meant a non statically known constraint. My example was not
> accurate enough then.
> 
>    type Vector is (Positive range <>) of Float;
> 
>    function Norm (V : in Vector) return Float;
> 
>    ...
> 
>    N := <runtime computed value>;
> 
>    declare
>       V : Vector (1 .. N);
>       R : Float;
>    begin
>       R := Norm (V);
>       ...


This won't convince a C++ programmer because they have typed
template Lisp, checked element access, container properties,
and stack allocated aggregates.

What C++ does not have is full nesting, including access to
auto variables of surrounding scopes and to function parameters.
(This can be of use as demonstrated by Integrate and Iterate.)
You can have local classes in C++ and even mimic local subprograms
but this is clumsy.

Ada nesting entails very straight forward lifetime control,
much underused IMHO. (Plus GNAT performance is not as good as
when everything is at library level.) Using scopes, you can
control static and dynamic lifetimes types and objects
(including tasks!).
But somehow I think people are obsessed with making each and
every type fully general and usable at library level (and in
theory books and papers?), simply dismissing possibilities that
declarative regions offer naturally. Is this a consequence of
teaching and hyping mostly flat languages?