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From: dewar@merv.cs.nyu.edu (Robert Dewar)
Subject: Re: Equality operator overloading in ADA 83
Date: 1997/04/25
Message-ID: <dewar.861970467@merv>#1/1
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References: <01bc4e9b$ac0e7fa0$72041dc2@lightning>
 <mheaney-ya023680002204970006190001@news.ni.net>
 <335CAEFE.35DC@elca-matrix.ch> <dewar.861864029@merv>
 <E9588B.FsE@world.std.com>
Organization: New York University
Newsgroups: comp.lang.ada
Date: 1997-04-25T00:00:00+00:00
List-Id: <comp.lang.ada>


Bob said

<<So, yes, you ought to change Bounded_String to be tagged, or else use
some special hack.  Unless of course you think WG9 will disapprove the
AI -- I doubt it.  I also remember you saying that such special hacks
are easy to implement in GNAT, so you could save one word per
Bounded_String, if you like.>>

That's right, I remember now. I had remembered the discussion about
unbounded strings, but forgot that we decided to extend it. In fact
avoiding the use of tagged types is much more than saving one word,
it saves dragging in all the tagged support stuff if you are not otherwise
using tagged types.

I think probably the nicest way of doing this is to introduce a pragma

pragma Compose_Equality (type-name);

yes, it's a bit aggressive, but then so is the ARG's decision, and if the
problem in the standard library is important enough to be worth the ARG
changing the language, it seems reasonable to spupose that other libraries
will need the same treatment.