From: "Randy Brukardt" <randy@rrsoftware.com>
Subject: Re: A bad counterintuitive behaviour of Ada about OO
Date: Fri, 8 Aug 2014 17:32:23 -0500
Date: 2014-08-08T17:32:23-05:00 [thread overview]
Message-ID: <ls3j5o$4hp$1@loke.gir.dk> (raw)
In-Reply-To: 2extr7bydwfw.tcda12f9xnq9.dlg@40tude.net
"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message
news:2extr7bydwfw.tcda12f9xnq9.dlg@40tude.net...
...
> The only case where this may happen is parallel type hierarchies when two
> types are inherited synchronously, e.g.
>
> type Object is tagged ...
> type Handle is tagged ...
> function Access (X : Handle_To_Object) return Object;
>
> type New_Object is new Object with ...
>
> must produce
>
> type New_Handle is new Handle with ...
>
> and
>
> function Access (X : New_Handle) return New_Object;
>
> No OOPL I know can handle this.
I've toyed with proposing this for Ada (seriously). The containers in
particular are tagged but cannot be usefully extended because of this
problem. It's unclear, though, that the model would actually work.
In any case, this is the only way to do covariance of unrelated types.
Otherwise, you're just in the realm of overloading (usually a better
solution anyway, IMHO).
Randy.
next prev parent reply other threads:[~2014-08-08 22:32 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-05 20:09 A bad counterintuitive behaviour of Ada about OO Victor Porton
2014-08-05 20:58 ` Simon Wright
2014-08-05 21:06 ` Victor Porton
2014-08-05 21:51 ` Niklas Holsti
2014-08-05 22:13 ` Victor Porton
2014-08-05 22:35 ` Victor Porton
2014-08-05 23:25 ` Adam Beneschan
2014-08-05 20:59 ` Dmitry A. Kazakov
2014-08-05 21:07 ` Victor Porton
2014-08-05 22:39 ` Shark8
2014-08-05 21:11 ` Victor Porton
2014-08-06 7:26 ` Dmitry A. Kazakov
2014-08-07 7:41 ` Maciej Sobczak
2014-08-07 8:50 ` Dmitry A. Kazakov
2014-08-08 7:54 ` Maciej Sobczak
2014-08-08 8:14 ` Dmitry A. Kazakov
2014-08-08 13:06 ` Maciej Sobczak
2014-08-08 13:22 ` Dmitry A. Kazakov
2014-08-08 22:32 ` Randy Brukardt [this message]
2014-08-09 16:11 ` Maciej Sobczak
2014-08-09 16:48 ` Dmitry A. Kazakov
2014-08-10 20:55 ` Maciej Sobczak
2014-08-11 7:41 ` Dmitry A. Kazakov
2014-08-11 7:58 ` Maciej Sobczak
2014-08-11 8:23 ` Dmitry A. Kazakov
2014-08-12 7:50 ` Maciej Sobczak
2014-08-11 11:35 ` G.B.
2014-08-08 22:26 ` Randy Brukardt
2014-08-08 8:34 ` Shark8
2014-08-08 12:59 ` Maciej Sobczak
2014-08-08 22:37 ` Randy Brukardt
2014-08-08 22:53 ` Jeffrey Carter
2014-08-07 8:58 ` J-P. Rosen
2014-08-07 9:40 ` Dmitry A. Kazakov
2014-08-07 11:17 ` J-P. Rosen
2014-08-07 12:28 ` Dmitry A. Kazakov
2014-08-07 13:34 ` J-P. Rosen
2014-08-07 16:10 ` Dmitry A. Kazakov
2014-08-07 18:14 ` Robert A Duff
2014-08-07 19:41 ` Dmitry A. Kazakov
2014-08-07 20:53 ` Robert A Duff
2014-08-08 7:43 ` Dmitry A. Kazakov
2014-08-08 8:18 ` Shark8
2014-08-08 7:45 ` J-P. Rosen
2014-08-08 8:04 ` Dmitry A. Kazakov
2014-08-08 8:55 ` J-P. Rosen
2014-08-08 9:13 ` Dmitry A. Kazakov
2014-08-08 10:01 ` J-P. Rosen
2014-08-08 10:53 ` Dmitry A. Kazakov
2014-08-08 10:56 ` Victor Porton
2014-08-08 12:00 ` J-P. Rosen
2014-08-08 13:11 ` Dmitry A. Kazakov
2014-08-08 13:53 ` J-P. Rosen
2014-08-08 20:23 ` Dmitry A. Kazakov
2014-08-07 20:29 ` Shark8
2014-08-08 7:49 ` J-P. Rosen
2014-08-08 8:12 ` Shark8
2014-08-08 8:26 ` Dmitry A. Kazakov
2014-08-08 11:10 ` Shark8
2014-08-08 11:20 ` Dmitry A. Kazakov
2014-08-08 19:34 ` Shark8
2014-08-08 20:23 ` Dmitry A. Kazakov
2014-08-07 15:03 ` Jeffrey Carter
2014-08-08 7:48 ` Maciej Sobczak
2014-08-08 8:51 ` J-P. Rosen
2014-08-08 13:25 ` Maciej Sobczak
2014-08-08 13:34 ` J-P. Rosen
2014-08-08 13:52 ` Dmitry A. Kazakov
2014-08-08 14:21 ` J-P. Rosen
2014-08-08 20:23 ` Dmitry A. Kazakov
2014-08-08 22:08 ` Randy Brukardt
2014-08-08 22:18 ` Randy Brukardt
2014-08-06 4:50 ` Per Sandberg
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