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From: mheaney@ni.net (Matthew Heaney)
Subject: Re: Tagged Types and Generics
Date: 1997/04/26
Message-ID: <mheaney-ya023680002604972101470001@news.ni.net>#1/1
X-Deja-AN: 237640966
References: <3.0.32.19970421225247.007129f4@mail.4dcomm.com>
 <dewar.862004577@merv>
Organization: Estormza Software
Newsgroups: comp.lang.ada
Date: 1997-04-26T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <dewar.862004577@merv>, dewar@merv.cs.nyu.edu (Robert Dewar) wrote:

>Bob Leif says
>
><<Background: Recently, Tom Moran, Randy Brukard and I wrote a paper. "Ada
>95, The Language Speaks for Itself".  This paper will appear in the May
>Object Magazine.  In this paper we modeled money as a decimal type and did
>inheritance directly via a generic.  I had suggested modeling money as a
>tagged type.  My co-authors very wisely vetoed that approach.  After the>>
>
>I can't see any reason for wanting to model money as a tagged type -- you
>lose literals, and you lose a lot of other useful semantics of decimal
>types, and you gain nothing  that I can see.

Agreed.  Derivation is a much more natural technique for modeling different
currencies.  See section 7.3 of the Ada 83 Rationale which uses that very
example.

<http://sw-eng.falls-church.va.us/AdaIC/standards/83rat/html/ratl-07-03.html
#7.3>

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Matthew Heaney
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