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-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,1116ece181be1aea
X-Google-Attributes: gid103376,public
X-Google-ArrivalTime: 2003-09-22 08:26:41 PST
Path: 
 archiver1.google.com!news1.google.com!newsfeed.stanford.edu!cyclone.bc.net!newspump.monmouth.com!newspeer.monmouth.com!nntp.abs.net!ash.uu.net!spool.news.uu.net!not-for-mail
Date: Mon, 22 Sep 2003 11:26:39 -0400
From: Hyman Rosen <hyrosen@mail.com>
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US;
 rv:1.5b) Gecko/20030917 Thunderbird/0.3a
X-Accept-Language: en-us, en
MIME-Version: 1.0
Newsgroups: comp.lang.ada
Subject: Re: Is the Writing on the Wall for Ada?
References: <mailman.20.1062997816.295.comp.lang.ada@ada.eu.org>
 <q697b.8261$w41.4773@nwrdny02.gnilink.net> <wvbrad9emn3u.fsf@sun.com>
 <u3cez82oh.fsf@earthlink.net> <wvbr65jul87d.fsf@sun.com>
 <uhe3d7hmj.fsf@earthlink.net> <xXt9b.4926$U41.4024@nwrdny01.gnilink.net>
 <ud6e178aw.fsf@earthlink.net>
 <568ede3c.0309160929.1d0d3d95@posting.google.com>
 <3F67AFB9.7040001@attbi.com> <OJO9b.1195$U6.228@nwrdny03.gnilink.net>
 <3F6F0841.60607@attbi.com>
In-Reply-To: <3F6F0841.60607@attbi.com>
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Transfer-Encoding: 7bit
Organization: KBC Financial Products
Message-ID: <1064244399.683441@master.nyc.kbcfp.com>
Cache-Post-Path: master.nyc.kbcfp.com!unknown@aphelion.nyc.kbcfp.com
X-Cache: nntpcache 3.0.1 (see http://www.nntpcache.org/)
NNTP-Posting-Host: 204.253.250.10
X-Trace: 1064244399  21122 204.253.250.10
Xref: archiver1.google.com comp.lang.ada:42749
Date: 2003-09-22T11:26:39-04:00
List-Id: <comp.lang.ada>

Robert I. Eachus wrote:
> No, it is not a moot point in Ada.

I still don't think we're talking about the same thing.

Suppose we have the following C++ situation: I have two
class types, IFoo and IBar, that are not under my control
(they come from two separate libraries, perhaps).

I am given a container of pointers to IFoo. Since C++ has
MI, it's possible that some of these IFoo pointers are
actually pointers to objects of a class which inherit both
from IFoo and IBar. Such a class can be created independently
of the definitions of IFoo and IBar. In any case, I do not
have access to the definitions or names of such classes, and
at the time I am given the following task, such classes may
not even exist yet.

I am tasked with finding such IFoo+IBar pointers in the
container and handing them off to a procedure which expects
to get IBar pointers. In C++, the solution is simple - given
an IFoo pointer, I call dynamic_cast<IBar *> on the pointer.
If the result is non-null, then I have a valid IBar pointer,
and I know that the underlying object inherits from both.

So, does Ada have an equivalent to this? Remember, you do not
control IFoo, IBar, the container type, or the implementation
of the type which is trying to be the combination of an IFoo
and an IBar.