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From: Shark8 <OneWingedShark@gmail.com>
Subject: Re: A bad counterintuitive behaviour of Ada about OO
Date: Fri, 08 Aug 2014 02:34:43 -0600
Date: 2014-08-08T02:34:43-06:00	[thread overview]
Message-ID: <FY%Ev.265543$wR1.208621@fx20.iad> (raw)
In-Reply-To: <536e35d6-f1de-4917-9300-26d78686eaf2@googlegroups.com>

On 08-Aug-14 01:54, Maciej Sobczak wrote:
> W dniu czwartek, 7 sierpnia 2014 10:50:52 UTC+2 użytkownik Dmitry A. Kazakov napisał:
>
>>> and no support for type covariance on return
>>> type Ada is way more broken than other languages I am aware of.
>>
>> I don't understand this. The return type is covariant in Ada.
>
> Can I have Better_Factory type with a primitive operation returning Better_Product?
>
> No, because Better_Product is a different type than Product and such operation
> would not be considered overriding. This works properly in just about any other
> language with support for OO.
>

Can't you use some class-wide functions, some primitive functions, and 
the Generic_Dispatching_Constructor function to do this?

IIRC something like:

   Type Base is abstract tagged null record;
   Function Product return Base is abstract; -- Primitive function.
   Function Get_Product return Base'Class;   -- Dispatches call to Product.
   -- Uses generic_dispatching constructor.
   Function Make(Stream : not null access
                          Ada.Streams.Root_Stream_Type'Class)
         return Base'Class;                  -- For Stream-creation.
   -- Perhaps some other creation functions.
   -- ...

   Type Child is tagged ...

Or am I misunderstanding you?

  parent reply	other threads:[~2014-08-08  8:34 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
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 [this message]
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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