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: 103376,585fd78267abd80c
X-Google-Attributes: gid103376,domainid0,public,usenet
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news1.google.com!news2.google.com!news1.google.com!border1.nntp.dca.giganews.com!nntp.giganews.com!wns13feed!worldnet.att.net!164.128.36.58!news.ip-plus.net!newsfeed.ip-plus.net!news.post.ch!not-for-mail
From: Martin Krischik <krischik@users.sourceforge.net>
Newsgroups: comp.lang.ada
Subject: Re: On pragma Precondition etc.
Date: Tue, 29 Jul 2008 13:18:37 +0200
Organization: Swisscom IP+ (post doesn't reflect views of Swisscom)
Message-ID: <488efc8d$1@news.post.ch>
References: <4889886d$0$18827$9b4e6d93@newsspool2.arcor-online.net>
 <Pine.LNX.4.64.0807251224010.10913@medsec1.medien.uni-weimar.de>
 <f9112d8f-1c5a-4533-88ed-b4c22d108ac8@q5g2000prf.googlegroups.com>
 <6etsi6F8mbmbU2@mid.individual.net>
NNTP-Posting-Host: 194.41.146.1
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
X-Trace: atlas.ip-plus.net 1217330321 17353 194.41.146.1 (29 Jul 2008 11:18:41
 GMT)
X-Complaints-To: abuse@ip-plus.net
NNTP-Posting-Date: Tue, 29 Jul 2008 11:18:41 +0000 (UTC)
User-Agent: Thunderbird 2.0.0.16 (Windows/20080708)
In-Reply-To: <6etsi6F8mbmbU2@mid.individual.net>
X-Original-NNTP-Posting-Host: w03duo.pnet.ch
X-Original-Trace: 29 Jul 2008 13:18:37 +0100, w03duo.pnet.ch
Xref: g2news1.google.com comp.lang.ada:1371
Date: 2008-07-29T13:18:37+02:00
List-Id: <comp.lang.ada>

Alex R. Mosteo schrieb:

> Piling more suggestions: I understand the point of using pragmas by Gnat at
> this stage, but if this is going to be standardized perhaps the syntax of a
> declaration could be changed. For example:
> 
> function Foo (X, Y : Something) return Whatever with
>   Precondition (Blah) and
>   Postcondition (Urgh);

It too think a dedicated syntax would be best. However, I suggest to 
take a good look at task and protected types for guidance.

Protected types already have an precondition. I know they are attached 
to the body and a protected type blocks until the condition becomes true.

But the idea behind is still similar and so should be the syntax. Now 
let me think:

Option 1:

using when - just like protected types.

function Foo (
    Integer X,Y)
entry when
    X > Y
exit when
    Foo  > X + Y
return
    Integer;

Option 2:

using nicer English.

function Foo (
    Integer X,Y)
on entry
    X > Y
on exit
    Foo  > X + Y
return
    Integer;

Both options would not need new keywords ;-)

And how about Invariants (http://en.wikipedia.org/wiki/Class_invariant)?

Martin

-- 
mailto://krischik@users.sourceforge.net
Ada programming at: http://ada.krischik.com