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=-0.3 required=5.0 tests=BAYES_00,
	REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,bdd718faa7c79f29
X-Google-Attributes: gid103376,public
X-Google-ArrivalTime: 2003-06-28 17:33:31 PST
Path: 
 archiver1.google.com!news1.google.com!newsfeed.stanford.edu!headwall.stanford.edu!newshub.sdsu.edu!elnk-pas-nf2!newsfeed.earthlink.net!stamper.news.pas.earthlink.net!stamper.news.atl.earthlink.net!harp.news.atl.earthlink.net!not-for-mail
From: Richard Riehle <richard@adaworks.com>
Newsgroups: comp.lang.ada
Subject: Re: Overlapping ranges
Date: Sat, 28 Jun 2003 17:36:33 -0700
Organization: AdaWorks Software Engineering
Message-ID: <3EFE3491.F968568D@adaworks.com>
References: <EU6Ja.43611$JA5.766429@news.xtra.co.nz>
Reply-To: richard@adaworks.com
NNTP-Posting-Host: 3f.bb.81.17
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
X-Server-Date: 29 Jun 2003 00:33:31 GMT
X-Mailer: Mozilla 4.7 [en] (Win98; I)
X-Accept-Language: en
Xref: archiver1.google.com comp.lang.ada:39878
Date: 2003-06-29T00:33:31+00:00
List-Id: <comp.lang.ada>

AG wrote:

> Assuming I have a package declaration like this:
>
> package range is
>   type x1 is range 0..255;
>   type x2 is range 127..2**15-1;
> end ranges;
>
> Is there a way to declare a function
> using that package that will accept
> values of either x1 or x2 (and nothing
> else) restricted to the range 127..255 ?

Perhaps I don't understand why this is a problem for
you.  Why not something such as,

package ranges is
  type Number is range 0..2**15-1;
  type x1 is new Number range 0..255;
  type x2 is new Number range 127..2**15-1;
  function Fudge (A : X1; B : X2) return Number'Base;
  function Fudge (A : X2; B : X1) return Number'Base;
  X2_Error   : exception;
  X1_Error   : exception;
end ranges;

Tested using the following procedure,

with ranges;
with Ada.Integer_Text_IO;
procedure Test_Ranges is
   First  : ranges.X1 := 128;
   Second : ranges.X2 := 130;
   Result : ranges.Number'Base;
begin
   Result := ranges.Fudge(A => First, B => Second);
   Ada.Integer_Text_IO.Put(Integer(Result));  --  258
end Test_Ranges;

With this as a possible implementation of the body,

package body ranges is

   function Fudge (A : X1; B : X2) return Number'Base is
   begin
     if A in X1 then
         return Number(A) + Number(B);
      else
         raise X1_Error;
      end if;
   end Fudge;

   function Fudge (A : X2; B : X1) return Number'Base is
   begin
      if A in X2 then
         return Number(A) + Number(B);
      else
         raise X2_Error;
      end if;
   end Fudge;
end ranges;