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From: bobduff@world.std.com (Robert A Duff)
Subject: Re: Question on modular types
Date: 1997/01/06
Message-ID: <E3LotB.9J9@world.std.com>#1/1
X-Deja-AN: 208118612
references: <01bbfa96$66d516a0$8d2d5c8b@jerryware> <dewar.852430006@merv>
 <01bbfbf8$4fda7a40$5f2d5c8b@jerryware>
organization: The World Public Access UNIX, Brookline, MA
newsgroups: comp.lang.ada
Date: 1997-01-06T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <01bbfbf8$4fda7a40$5f2d5c8b@jerryware>,
Jerry van Dijk <jvandyk@ibm.net> wrote:
>However, 4.5.4(1) mentions that all unary adding operators have their
>conventional
>meaning, and since the note is not technically part of the standard,
>that leaves
>me wondering wat that 'conventional meaning; might be. And
>'conventional' to whom ?

Convention to those who have read the RM, and understand that arithmetic
on modular types is always wrap-around arithmetic.  ;-)

We called them "modular", and not "unsigned", after all.  If you just
want nonnegative values, then "type T is range 0..2**8-1;" or some such
thing is more likely what you want.  The problem with *that*, of course,
is that it doesn't work if the upper bound is higher than the upper
bound of the largest *signed* integer type -- e.g. "type T is range
0..2**64-1;" will not work in GNAT.

- Bob