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,f5508b044317ceed
X-Google-Attributes: gid103376,public,usenet
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news1.google.com!news2.google.com!news.glorb.com!newscon02.news.prodigy.net!prodigy.net!newsfeed-00.mathworks.com!nntp.TheWorld.com!not-for-mail
From: Robert A Duff <bobduff@shell01.TheWorld.com>
Newsgroups: comp.lang.ada
Subject: Re: Question about controlled types.
Date: Thu, 07 Feb 2008 11:30:51 -0500
Organization: The World Public Access UNIX, Brookline, MA
Message-ID: <wccprv8loec.fsf@shell01.TheWorld.com>
References: <47aa5ca6$0$32487$4d3efbfe@news.sover.net>
 <O9wqj.10053$EK3.1584@trndny04>
NNTP-Posting-Host: shell01.theworld.com
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
X-Trace: pcls6.std.com 1202401853 9221 192.74.137.71 (7 Feb 2008 16:30:53 GMT)
X-Complaints-To: abuse@TheWorld.com
NNTP-Posting-Date: Thu, 7 Feb 2008 16:30:53 +0000 (UTC)
User-Agent: Gnus/5.1008 (Gnus v5.10.8) Emacs/21.3 (irix)
Cancel-Lock: sha1:JZCC2F+/sS69nW4QVTm79USE5kE=
Xref: g2news1.google.com comp.lang.ada:19730
Date: 2008-02-07T11:30:51-05:00
List-Id: <comp.lang.ada>

Hyman Rosen <hyrosen@mail.com> writes:

> There are reasons for doing assignment like this in Ada (or
> at least I think so - I don't really know Ada), but the C++
> assignment operator model is much cleaner.

Right, the C++ way has the advantage that a single operation can get its
hands on the left- and right-hand sides at the same time.  The reason
Ada doesn't have this feature is that we couldn't figure out how to make
it work for records whose discriminants can change.  And we couldn't
simply outlaw that case, because it would introduce a violation of the
generic contract model.

- Bob