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=-1.9 required=5.0 tests=BAYES_00 autolearn=ham
	autolearn_force=no version=3.4.4
X-Google-Thread: a07f3367d7,421f00454ed1208d
X-Google-Attributes: gida07f3367d7,public,usenet
X-Google-NewGroupId: yes
X-Google-Language: ENGLISH,ASCII
Path: 
 g2news2.google.com!postnews.google.com!x1g2000prh.googlegroups.com!not-for-mail
From: Adam Beneschan <adam@irvine.com>
Newsgroups: comp.lang.ada
Subject: Re: SPARK - runtime checks question
Date: Fri, 19 Jun 2009 11:33:32 -0700 (PDT)
Organization: http://groups.google.com
Message-ID: <14f911e0-bd4c-4068-bae7-3d234cbed652@x1g2000prh.googlegroups.com>
References: 
 <8d79ac48-d35d-4717-aca3-68f036de0de3@f16g2000vbf.googlegroups.com>
NNTP-Posting-Host: 66.126.103.122
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
X-Trace: posting.google.com 1245436413 8845 127.0.0.1 (19 Jun 2009 18:33:33
 GMT)
X-Complaints-To: groups-abuse@google.com
NNTP-Posting-Date: Fri, 19 Jun 2009 18:33:33 +0000 (UTC)
Complaints-To: groups-abuse@google.com
Injection-Info: x1g2000prh.googlegroups.com; posting-host=66.126.103.122;
	posting-account=duW0ogkAAABjRdnxgLGXDfna0Gc6XqmQ
User-Agent: G2/1.0
X-HTTP-UserAgent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; WOW64;
	SLCC1; .NET CLR 2.0.50727; Media Center PC 5.0; .NET CLR 3.5.21022; .NET CLR
	3.5.30729; .NET CLR 3.0.30618),gzip(gfe),gzip(gfe)
Xref: g2news2.google.com comp.lang.ada:6545
Date: 2009-06-19T11:33:32-07:00
List-Id: <comp.lang.ada>

On Jun 19, 8:26=A0am, Maciej Sobczak <see.my.homep...@gmail.com> wrote:
> Consider the following:
>
> -- my_package.ads:
> package My_Package is
> =A0 =A0function Distance (X : in Natural; Y : in Natural) return Natural;
> end My_Package;
>
> -- my_package.adb:
> package body My_Package is
>
> =A0 =A0function Distance (X : in Natural; Y : in Natural) return Natural
> =A0 =A0is
> =A0 =A0 =A0 Result : Natural;
> =A0 =A0begin
> =A0 =A0 =A0 if X > Y then
> =A0 =A0 =A0 =A0 =A0Result :=3D X - Y; =A0 =A0// line 8
> =A0 =A0 =A0 else
> =A0 =A0 =A0 =A0 =A0Result :=3D Y - X; =A0 =A0// line 10
> =A0 =A0 =A0 end if;
> =A0 =A0 =A0 return Result;
> =A0 =A0end Distance;
>
> end My_Package;

Apologies in advance for answering a question you didn't ask, but...
any reason not to simply return abs(X-Y)?  If you're thinking that the
result of X-Y will raise a Constraint_Error if it's negative---it
won't.  (At least not in Ada.  I don't know much about SPARK---it
wouldn't raise Constraint_Error there either, would it?)

                                -- Adam