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-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,48fa8e3cfaec41af
X-Google-Attributes: gid103376,public
X-Google-ArrivalTime: 2002-07-22 11:12:13 PST
Path: 
 archiver1.google.com!news1.google.com!newsfeed.stanford.edu!canoe.uoregon.edu!hammer.uoregon.edu!skates!not-for-mail
From: Stephen Leake <stephen.a.leake.1@gsfc.nasa.gov>
Newsgroups: comp.lang.ada
Subject: Re: worth the hassle?
Date: 22 Jul 2002 14:06:31 -0400
Organization: NASA Goddard Space Flight Center (skates.gsfc.nasa.gov)
Message-ID: <ud6tfljrs.fsf@gsfc.nasa.gov>
References: <ZPW_8.1457$tg4.87971@newsfep1-win.server.ntli.net>
 <xHX_8.1635$tg4.100380@newsfep1-win.server.ntli.net>
NNTP-Posting-Host: anarres.gsfc.nasa.gov
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
X-Trace: skates.gsfc.nasa.gov 1027361720 5598 128.183.220.71 (22 Jul 2002
 18:15:20 GMT)
X-Complaints-To: usenet@news.gsfc.nasa.gov
NNTP-Posting-Date: 22 Jul 2002 18:15:20 GMT
User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.2
Xref: archiver1.google.com comp.lang.ada:27308
Date: 2002-07-22T18:15:20+00:00
List-Id: <comp.lang.ada>

"chris.danx" <spamoff.danx@ntlworld.com> writes:

> hmm, problem...
> <snip code>
> 
> Let's say we have 2 types (a_type & b_type) derived from a single type,
> base_type and we want to store objects of all three types in the *same
> list*.  How do we code assign for this situation?  What happens if the
> derved classes are not known before hand?  Is it even possible to put the
> all the types in the same list?

Use a class-wide access type in the list:

type Element_Access is access all Element_Type'class;

To mangle someone else's quote: "there is almost no problem in
computer science that a layer of indirection won't solve".

-- 
-- Stephe