From: rick H <rik_nntp@dsl.pipex.com>
Subject: Re: Instantiating private types with discriminants?
Date: Tue, 09 May 2006 14:24:13 GMT
Date: 2006-05-09T14:24:13+00:00 [thread overview]
Message-ID: <hC18g.28777$Nb2.521756@news1.nokia.com> (raw)
In-Reply-To: 1147183013.687672.246320@g10g2000cwb.googlegroups.com
Brenta <ludovic@ludovic-brenta.org> wrote:
>> with Discrim; use Discrim;
>> procedure Use_Discrim is
>> A : Type_A_Ptr; -- public implementation
>> B : Type_B_Ptr; -- private implementation
>> begin
>> A := new Type_A'(Param => 100); -- qualified expression
>> B := new Type_B (Param => 123); -- type conversion
>> end Use_Discrim;
>>
>> So, my question to the experts is: Why does "privatising" a type's
>> details change the way that you "new" instantiations of it?
>
> Actually, the declaration of B is not a type conversion; it is an
> allocator that uses a subtype_mark, as opposed to a
> qualified_expression (see ARM 4.8(2)).
Thanks, Ludovic - especially for the ARM references. I now understand
that the expression for B was not a type conversion - though to a novice
it resembles one : a subtype_mark followed by something in brackets!
You say that B is an allocator with a subtype_mark - but ARM 3.2.2
suggests to me (probably wrong!) that it's a subtype_indication, because
it has a constraint (the discriminant).
--
Rick
next prev parent reply other threads:[~2006-05-09 14:24 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-09 13:17 Instantiating private types with discriminants? rick H
2006-05-09 13:45 ` Georg Bauhaus
2006-05-09 14:06 ` rick H
2006-05-09 13:56 ` Ludovic Brenta
2006-05-09 14:24 ` rick H [this message]
2006-05-09 19:48 ` Ludovic Brenta
2006-05-09 14:05 ` Dmitry A. Kazakov
2006-05-09 14:48 ` rick H
2006-05-09 15:20 ` Jerry Petrey
2006-05-09 15:42 ` rick H
2006-05-09 15:53 ` Avoiding use Ada.Tags (was Re: Instantiating private types with discriminants?) Alex R. Mosteo
2006-05-09 16:01 ` Instantiating private types with discriminants? Dmitry A. Kazakov
2006-05-10 7:42 ` rick H
2006-05-10 9:09 ` Ludovic Brenta
2006-05-10 11:49 ` Georg Bauhaus
2006-05-10 13:44 ` rick H
2006-05-10 14:21 ` Ludovic Brenta
2006-05-10 15:10 ` rick H
2006-05-10 15:45 ` Ludovic Brenta
2006-05-10 14:41 ` Dmitry A. Kazakov
2006-05-10 15:34 ` rick H
2006-05-10 19:01 ` Georg Bauhaus
2006-05-10 19:05 ` Ludovic Brenta
2006-05-10 21:52 ` Rick H
2006-05-11 1:17 ` Jeffrey R. Carter
2006-05-11 7:44 ` Dmitry A. Kazakov
2006-05-11 8:27 ` rick H
2006-05-11 10:28 ` Dmitry A. Kazakov
2006-05-11 15:59 ` Robert A Duff
2006-05-12 7:37 ` Dmitry A. Kazakov
2006-05-12 9:24 ` Georg Bauhaus
2006-05-12 12:40 ` Dmitry A. Kazakov
2006-05-12 18:25 ` Randy Brukardt
2006-05-09 19:57 ` "Use" and "=" for Tags (was: Re: Instantiating private types with discriminants?) Jeffrey R. Carter
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