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From: bobduff@world.std.com (Robert A Duff)
Subject: Re: Equality operator overloading in ADA 83
Date: 1997/04/23
Message-ID: <E93v4u.DG1@world.std.com>#1/1
X-Deja-AN: 236864358
References: <01bc4e9b$ac0e7fa0$72041dc2@lightning> <E91zFw.KDE@world.std.com>
 <mheaney-ya023680002204972109430001@news.ni.net>
 <335E0B1F.12C9@elca-matrix.ch>
Organization: The World Public Access UNIX, Brookline, MA
Newsgroups: comp.lang.ada
Date: 1997-04-23T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <335E0B1F.12C9@elca-matrix.ch>,
Mats Weber  <Mats.Weber@elca-matrix.ch> wrote:
>> Composability should always be guaranteed by user-defined types, too.
>
>There seems to be much disagreement on this question for all kinds of
>reasons. But I agree with you 100%.

I think I agree that "=" should compose, in the sense that composite
types call the user-defined "=" of their components, and the predefined
"=" doesn't "re-emerge" in generics.  But how far do you think we should
carry this?  E.g. if "=" is redefined for a scalar type, does that
affect case statements on that type?  After all, case stms check the
case expression for equality with some values.  What about operators
other than "="?  If "/" is redefined for an integer type, should
Text_IO.Integer_IO know about it?  It might well make Put(some-integer)
do the "wrong" thing, since the generic might need to divide by 10.

If I redefine "<" on a scalar type, should "<" on an array-of-that-type
call it?

- Bob