From: Adam Beneschan <adam@irvine.com>
Subject: Re: Self pointer in limited record
Date: Fri, 31 Aug 2007 10:37:10 -0700
Date: 2007-08-31T10:37:10-07:00 [thread overview]
Message-ID: <1188581830.368058.72900@l22g2000prc.googlegroups.com> (raw)
In-Reply-To: <1188578849.187422.280620@50g2000hsm.googlegroups.com>
On Aug 31, 9:47 am, amado.al...@gmail.com wrote:
> On 4 Jul, 20:31, Maciej Sobczak <see.my.homep...@gmail.com> wrote:
>
> > Consider:
>
> > type T_Access is access all T;
> > type T is new Ada.Finalization.Limited_Controlled with record
> > Self: T_Access := T'Unchecked_Access;
> > -- more components
> > -- ...
> > end record;
>
> > I have seen this pattern repeatedly.
>
> Then you have seen illegal Ada code repeatedly. I wish this were
> possible myself. Or more simply:
>
> type T is -- limited or not
> Self : access T := T'Unchecked_Access;
> ...
> end;
>
> But the compiler will remind you that Unchecked_Access is not
> available for types.
No, this can be legal. Normally, you can't apply 'Unchecked_Access to
a type name. But within the definition of a type T, the use of T in a
context like this refers to the "current instance"; that is, it will
refer to whatever object is declared with that type. So if you later
declare "X : T;", then the T in T'Unchecked_Access will be replaced by
X for that declaration (and X.Self will thus point to X). See
8.6(17). However, it's only legal if T is limited (in Ada 2005, the
rule is slightly more restrictive), because 'Unchecked_Access can only
be applied to an aliased entity, and 3.10(9) says that the current
instance of a *limited* type is defined to be aliased.
-- Adam
next prev parent reply other threads:[~2007-08-31 17:37 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-04 19:31 Self pointer in limited record Maciej Sobczak
2007-07-05 8:22 ` Dmitry A. Kazakov
2007-07-05 10:35 ` Maciej Sobczak
2007-07-05 11:01 ` Pascal Obry
2007-07-05 11:14 ` Georg Bauhaus
2007-07-05 12:36 ` Dmitry A. Kazakov
2007-08-31 16:47 ` amado.alves
2007-08-31 17:09 ` Pascal Obry
2007-08-31 17:37 ` Adam Beneschan [this message]
2007-08-31 18:26 ` Jeffrey R. Carter
2007-08-31 19:33 ` Dmitry A. Kazakov
2007-09-01 13:33 ` Georg Bauhaus
2007-09-01 13:46 ` Dmitry A. Kazakov
2007-09-01 14:15 ` Georg Bauhaus
2007-09-01 16:03 ` Dmitry A. Kazakov
2007-09-01 19:49 ` Georg Bauhaus
2007-09-01 20:09 ` Dmitry A. Kazakov
2007-09-02 21:37 ` Georg Bauhaus
[not found] ` <re7ei5lc7dzf$.11qtcnh35jmzg$.dlg@40tude.net>
2007-09-03 10:51 ` Georg Bauhaus
2007-09-03 14:17 ` Dmitry A. Kazakov
2007-09-03 15:55 ` Jean-Pierre Rosen
2007-09-03 19:17 ` Dmitry A. Kazakov
2007-09-03 19:32 ` Markus E L
2007-09-03 20:14 ` Georg Bauhaus
2007-09-04 8:24 ` Dmitry A. Kazakov
2007-09-04 9:36 ` Jean-Pierre Rosen
2007-09-04 10:14 ` Dmitry A. Kazakov
2007-09-05 10:49 ` Georg Bauhaus
2007-09-05 12:04 ` Dmitry A. Kazakov
2007-09-05 13:12 ` Jean-Pierre Rosen
2007-09-05 15:10 ` Dmitry A. Kazakov
2007-09-05 16:25 ` Jean-Pierre Rosen
2007-09-05 19:52 ` Dmitry A. Kazakov
2007-09-06 7:19 ` Jean-Pierre Rosen
2007-09-06 9:28 ` Dmitry A. Kazakov
2007-09-06 11:53 ` Jean-Pierre Rosen
2007-09-06 15:35 ` Dmitry A. Kazakov
2007-09-05 18:31 ` Georg Bauhaus
2007-09-05 19:52 ` Dmitry A. Kazakov
2007-09-05 21:38 ` Georg Bauhaus
2007-09-06 7:37 ` Dmitry A. Kazakov
2007-09-06 10:26 ` Georg Bauhaus
2007-09-06 12:25 ` Dmitry A. Kazakov
2007-09-08 1:27 ` Randy Brukardt
2007-09-06 9:14 ` Markus E L
2007-09-06 9:48 ` Dmitry A. Kazakov
2007-09-04 8:23 ` Jean-Pierre Rosen
2007-10-31 23:59 ` adaworks
2007-09-03 20:38 ` Georg Bauhaus
2007-09-04 8:24 ` Dmitry A. Kazakov
2007-09-03 7:54 ` Jean-Pierre Rosen
2007-09-01 15:33 ` Markus E L
2007-09-04 14:55 ` Adam Beneschan
2007-09-04 15:09 ` Jean-Pierre Rosen
2007-09-08 1:36 ` Randy Brukardt
2007-09-04 17:31 ` Georg Bauhaus
2007-09-08 1:16 ` Randy Brukardt
2007-09-10 16:27 ` amado.alves
2007-09-10 17:13 ` Adam Beneschan
2007-09-10 19:00 ` Dmitry A. Kazakov
2007-09-11 3:12 ` Randy Brukardt
2007-09-11 9:38 ` Dmitry A. Kazakov
2007-09-12 21:57 ` Randy Brukardt
2007-09-13 8:03 ` Dmitry A. Kazakov
2007-09-13 21:37 ` Randy Brukardt
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