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,FREEMAIL_FROM
	autolearn=ham autolearn_force=no version=3.4.4
X-Google-Thread: a07f3367d7,5a88548f1bcf3510
X-Google-Attributes: gida07f3367d7,public,usenet
X-Google-NewGroupId: yes
X-Google-Language: ENGLISH,UTF8
Received: by 10.66.81.195 with SMTP id c3mr943977pay.44.1353056958846;
        Fri, 16 Nov 2012 01:09:18 -0800 (PST)
Path: 
 6ni88081pbd.1!nntp.google.com!npeer01.iad.highwinds-media.com!news.highwinds-media.com!feed-me.highwinds-media.com!border3.nntp.dca.giganews.com!border1.nntp.dca.giganews.com!border4.nntp.dca.giganews.com!border2.nntp.dca.giganews.com!nntp.giganews.com!novia!news-hub.siol.net!news1.t-com.hr!newsfeed.CARNet.hr!aioe.org!.POSTED!not-for-mail
From: =?utf-8?Q?Yannick_Duch=C3=AAne_=28Hibou57?=
 =?utf-8?Q?=29?=
 <yannick_duchene@yahoo.fr>
Newsgroups: comp.lang.ada
Subject: Re: Overring function and its returned type
Date: Fri, 09 Nov 2012 10:14:32 +0100
Organization: Ada @ Home
Message-ID: <op.wnh1aik1ule2fv@cardamome>
References: <op.wnhvol1wule2fv@cardamome>
 <1vej4u29b8e4z$.289wazkl31wg$.dlg@40tude.net>
NNTP-Posting-Host: aWaWeUaBdaj2Zzc04J1v5A.user.speranza.aioe.org
Mime-Version: 1.0
X-Complaints-To: abuse@aioe.org
User-Agent: Opera Mail/12.02 (Linux)
X-Notice: Filtered by postfilter v. 0.8.2
X-Received-Bytes: 3003
Content-Type: text/plain; charset=utf-8; format=flowed; delsp=yes
Content-Transfer-Encoding: Quoted-Printable
Date: 2012-11-09T10:14:32+01:00
List-Id: <comp.lang.ada>

Le Fri, 09 Nov 2012 09:24:18 +0100, Dmitry A. Kazakov  =

<mailbox@dmitry-kazakov.de> a =C3=A9crit:

> On Fri, 09 Nov 2012 08:13:23 +0100, Yannick Duch=C3=AAne (Hibou57) wro=
te:
>
>>            overriding
>>            function F
>>              (E : T)
>>               return R'Class -- Not overriding :-(
>>               is abstract;
>
> What is this? "overriding" + "abstract" does not make sense.

Overriding sometime do nothing, just remind something, recall an inherit=
ed  =

definition explicitly. Not the same, but a bit comparable to subtyping  =

used for type renaming (except I hate the latter and rather like the  =

former).

Overriding may also be used to add a postcondition or replace a class wi=
de  =

precondition by another.

I you prefer, you can instead think of `P3.F` returning `P3.R'Class`  =

instead of `P1.R'Class`, which would be overriding in the strict way you=
  =

expect.

> In any case it is the default. When you do nothing, you get F through
> inheritance and it is abstract when the parent's F was.

I know, but sometime you want something more explicit.

> Ada's declarations are not idempotent, in the sense that you cannot  =

> repeat
> them like you could in C++. So "F ... is abstract" always
> overloads/conflicts.

I don't get conflict when it happens I do it, it works fine.

> P.S. They should really have used the syntax with the keyword  =

> "overriding"
> trailing behind "is" rather than preceding "function/procedure."

Matter of taste. Personally, it happens I think I would have preferred  =

=E2=80=9Cnew=E2=80=9D instead of =E2=80=9Cnot overriding=E2=80=9D, but I=
 don't mind too much. That's to be  =

added to the list of tiny things which may be nice, but not required.


-- =

=E2=80=9CSyntactic sugar causes cancer of the semi-colons.=E2=80=9D [1]
=E2=80=9CStructured Programming supports the law of the excluded muddle.=
=E2=80=9D [1]
[1]: Epigrams on Programming =E2=80=94 Alan J. =E2=80=94 P. Yale Univers=
ity