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From: Florian Weimer <fw@deneb.enyo.de>
Subject: Re: Preventing type extensions
Date: Mon, 13 Sep 2010 07:32:02 +0200
Date: 2010-09-13T07:32:02+02:00	[thread overview]
Message-ID: <87d3sib44t.fsf@mid.deneb.enyo.de> (raw)
In-Reply-To: 66a3704c-54f9-4f04-8860-aa12f516134b@t3g2000vbb.googlegroups.com

* Maciej Sobczak:

> If it implements an abstract interface, then why extending it further
> is a problem? From the user point of view (that is, from the point of
> view of the subprogram that accepts Some_Interface'Class and operates
> on it), it does not matter how deep is the hierarchy.

Type extensions break encapsulation (at least if there non-abstract
dispatching subprograms which contain some non-trivial code): the
information which subprograms call each other under what circumstances
leaks to the outside of the package.  One very drastic way to
implement that is to disallow type extensions for most non-abstract
types you write, and consider the exceptions carefully.



  reply	other threads:[~2010-09-13  5:32 UTC|newest]

Thread overview: 107+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-09-12 10:18 Preventing type extensions Florian Weimer
2010-09-12 11:59 ` Ludovic Brenta
2010-09-12 12:53   ` Florian Weimer
2010-09-12 21:23     ` Maciej Sobczak
2010-09-13  5:32       ` Florian Weimer [this message]
2010-09-13  7:13         ` Dmitry A. Kazakov
2010-09-13  9:19           ` Georg Bauhaus
2010-09-13  9:42             ` Dmitry A. Kazakov
2010-09-13 10:23               ` Niklas Holsti
2010-09-13 12:55                 ` Cyrille
2010-09-13 13:55                   ` Dmitry A. Kazakov
2010-09-13 21:13                   ` J-P. Rosen
2010-09-21 13:57                     ` Cyrille
2010-09-21 14:19                       ` Dmitry A. Kazakov
2010-09-21 14:44                         ` Cyrille
2010-09-21 16:25                           ` Dmitry A. Kazakov
2010-09-21 17:11                             ` Georg Bauhaus
2010-09-21 18:11                               ` Dmitry A. Kazakov
2010-09-23 20:00                                 ` Simon Wright
2010-09-23 20:49                                   ` Dmitry A. Kazakov
2010-09-24  9:10                                     ` Georg Bauhaus
2010-09-24 10:24                                       ` Dmitry A. Kazakov
2010-09-24 13:30                                 ` Niklas Holsti
2010-09-24 16:27                                   ` Dmitry A. Kazakov
2010-09-24 17:47                                     ` Niklas Holsti
2010-09-24 19:42                                       ` Dmitry A. Kazakov
2010-09-21 14:32                       ` J-P. Rosen
2010-09-21 15:02                         ` Cyrille
2010-09-21 15:26                           ` J-P. Rosen
2010-09-21 16:18                             ` Cyrille
2010-09-22  8:01                               ` J-P. Rosen
2010-09-22 17:28                                 ` Cyrille
2010-09-22 19:30                                   ` Ludovic Brenta
2010-09-22 19:51                                     ` Florian Weimer
2010-09-22 20:14                                       ` Dmitry A. Kazakov
2010-09-22 20:25                                         ` Florian Weimer
2010-09-22 20:38                                           ` Dmitry A. Kazakov
2010-09-22 21:25                                             ` Vinzent Hoefler
2010-09-22 21:20                                           ` Georg Bauhaus
2010-09-22 20:16                                       ` Ludovic Brenta
2010-09-22 20:34                                         ` Florian Weimer
2010-09-22 22:45                                           ` Britt Snodgrass
2010-09-23  8:02                                           ` Ludovic Brenta
2010-09-23 16:51                                     ` Pascal Obry
2010-09-23 18:37                                       ` Florian Weimer
2010-09-23 18:55                                         ` Pascal Obry
2010-09-23 20:28                                       ` Ludovic Brenta
2010-09-24  9:20                                         ` Ludovic Brenta
2010-09-24 14:49                                           ` Simon Wright
2010-09-24 15:09                                             ` Ludovic Brenta
2010-09-24 16:21                                           ` Robert A Duff
2010-09-25  7:10                                         ` Pascal Obry
2010-09-25 12:03                                           ` Brian Drummond
2010-09-24  8:16                                   ` J-P. Rosen
2010-09-24  8:39                                     ` Cyrille
2010-09-24  9:27                                       ` Cyrille
2010-09-29 16:47                                         ` J-P. Rosen
2010-09-30 10:08                                           ` Cyrille
2010-10-05 17:02                                             ` J-P. Rosen
2010-10-08  7:50                                               ` Cyrille
2010-10-08 13:58                                               ` Cyrille
2010-10-08 20:12                                                 ` Dmitry A. Kazakov
2010-10-11  7:57                                                   ` Cyrille
2010-10-11  8:24                                                     ` Dmitry A. Kazakov
2010-10-12  5:23                                                   ` Shark8
2010-10-13  9:06                                                 ` J-P. Rosen
2010-10-13 17:37                                                   ` Cyrille
2010-10-13 18:50                                                     ` Dmitry A. Kazakov
2010-09-21 14:50                       ` (see below)
2010-09-21 17:37                         ` Cyrille
2010-09-21 19:07                           ` (see below)
2010-09-13 13:05                 ` Dmitry A. Kazakov
2010-09-13 20:21                   ` Niklas Holsti
2010-09-13 21:00                     ` Dmitry A. Kazakov
2010-09-13 21:10                 ` J-P. Rosen
2010-09-14 12:16                   ` Niklas Holsti
2010-09-14 16:46                     ` Dmitry A. Kazakov
2010-09-14 18:08                       ` Niklas Holsti
2010-09-14 18:32                         ` Niklas Holsti
2010-09-15  8:18                         ` Dmitry A. Kazakov
2010-09-14 17:04                     ` J-P. Rosen
2010-09-13 15:12               ` Securing type extensions (was: Preventing type extensions) Georg Bauhaus
2010-09-13 15:29                 ` Securing type extensions Dmitry A. Kazakov
2010-09-13 17:23                 ` Simon Wright
2010-09-13 20:22                   ` Georg Bauhaus
2010-09-13 20:41                     ` Dmitry A. Kazakov
2010-09-14 10:02                       ` Georg Bauhaus
2010-09-14 12:22                         ` Dmitry A. Kazakov
2010-09-14 21:18                           ` Georg Bauhaus
2010-09-15  8:15                             ` Dmitry A. Kazakov
2010-09-15 20:47                               ` Georg Bauhaus
2010-09-16  7:47                                 ` Dmitry A. Kazakov
2010-09-16 11:52                                   ` Georg Bauhaus
2010-09-16 12:45                                     ` Dmitry A. Kazakov
2010-09-16 20:53                                       ` Georg Bauhaus
2010-09-16 21:37                                         ` Dmitry A. Kazakov
2010-09-17  8:45                                           ` Georg Bauhaus
2010-09-17  9:39                                             ` Dmitry A. Kazakov
2010-10-05  5:59                     ` Randy Brukardt
2010-09-13 18:32           ` Preventing " Florian Weimer
2010-09-13 20:30             ` Dmitry A. Kazakov
2010-09-22 19:41               ` Florian Weimer
2010-09-22 20:34                 ` Dmitry A. Kazakov
2010-09-22 21:10                   ` Georg Bauhaus
2010-09-17  0:16           ` Shark8
2010-09-17  7:04             ` AdaMagica
2010-09-17 21:05               ` Shark8
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