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: 103376,18f7f6e041b3e0bf
X-Google-Attributes: gid103376,public
X-Google-ArrivalTime: 2002-07-24 15:55:56 PST
Newsgroups: comp.lang.ada
Path: 
 archiver1.google.com!news1.google.com!newsfeed.stanford.edu!canoe.uoregon.edu!arclight.uoregon.edu!news.tufts.edu!uunet!dca.uu.net!ash.uu.net!world!news
From: Robert A Duff <bobduff@shell01.TheWorld.com>
Subject: Re: Dispatching and generics - language lawyer question
Sender: news@world.std.com (Mr Usenet Himself)
Message-ID: <wccadogviqx.fsf@shell01.TheWorld.com>
Date: Wed, 24 Jul 2002 22:55:18 GMT
References: <mailman.1027489082.2047.comp.lang.ada@ada.eu.org>
NNTP-Posting-Host: shell01.theworld.com
Organization: The World Public Access UNIX, Brookline, MA
X-Newsreader: Gnus v5.7/Emacs 20.7
Xref: archiver1.google.com comp.lang.ada:27371
Date: 2002-07-24T22:55:18+00:00
List-Id: <comp.lang.ada>

"Grein, Christoph" <christoph.grein@eurocopter.com> writes:

> For untagged types, _redefined_ equality does not correctly compose and 
> _predefined_ equality reemerges in generics if not properly transferred by a 
> formal parameter:

What do you think the rule *should* be?  It does seem bad that
predefined "=" reemerges.  And of course the rule for "/=" should be the
same as for "=".

What about "<"?  Should the predefined one reemerge?  If a generic
sorting package calls the primitive "<" of the generic formal type,
it would seem desirable to use the user-defined one, rather than the
predefined one.

But what about "+" and "mod" and so forth?  Package Text_IO.Integer_IO
probably uses the predefined "mod" to format the number as a string.
But the *spec* of that package doesn't say that -- it just says the
string is formatted according to some rules.  If the predefined "mod"
did *not* reemerge, then a user-defined "mod" operator would break
Text_IO.Integer_IO.  You may say, "tough luck; that's the programmer's
fault".  But how should the semantics of Integer_IO be defined in the
RM?  Surely the use of "mod" there is an implementation detail.

- Bob