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=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID
	autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,a3471634bf10bf8d
X-Google-Attributes: gid103376,public
From: "Patrick D. Rogers" <p_rogers@hso.link.com>
Subject: Re: private type discriminants ignored?
Date: 1998/04/28
Message-ID: <354612AF.41C6@hso.link.com>#1/1
X-Deja-AN: 348479793
Content-Transfer-Encoding: 7bit
References: <rz84szje1ol.fsf@cs.williams.edu> <Es3A4J.Ion@world.std.com>
 <35460201.ED1315C4@hso.link.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Organization: NASA, Kennedy Space Center
Newsgroups: comp.lang.ada
Date: 1998-04-28T00:00:00+00:00
List-Id: <comp.lang.ada>


Samuel T. Harris wrote:
> 
> Robert A Duff wrote:
> >
> > In article <rz84szje1ol.fsf@cs.williams.edu>,
> > Jay Sachs  <sachs@cs.williams.edu> wrote:
> > >       type Stack(Size : Integer := 100) is private;
> >
> > >...  What is the reason that the default initialization
> > >seems to be ignored in the discriminant for the private type?
> >
> > The default isn't being ignored; Size is being correctly initialized to
> > 100.  However, the mere presence of a default means that the
> > discriminant can change.  That's confusing, and is a language design
> > flaw, IMHO.  There should have been a separate keyword or some other
> > separate syntax to mean "the discrim might change".  But as it is in
> > Ada, an unconstrained variable of type Stack can later have a discrim of
> > Integer'Last, even though it defaults initially to 100.  And many
> > compilers take the (quite reasonable) attitude that implicit heap
> > allocation is evil, so they allocate the maximum possible size for these
> > things.  And in this case, that's enormous, and will typically raise
> > Storage_Error; hence the warning.
> 
> Not entirely accurate. The mere presense of the default value does
> not mean the discriminant can change. It depends on how objects
> are declared.


Sam,

Since we are in pedantic mode, :) Bob said "... unconstrained variable
...", so he is indeed entirely accurate.

:) 


--pat

Patrick Rogers