From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Controlled types and exception safety
Date: Tue, 6 Dec 2005 10:50:22 +0100
Date: 2005-12-06T10:50:26+01:00 [thread overview]
Message-ID: <3trncoj4t0va.19bs46zhm4xbe.dlg@40tude.net> (raw)
In-Reply-To: dn3jvn$fdg$1@sunnews.cern.ch
On Tue, 06 Dec 2005 10:00:39 +0100, Maciej Sobczak wrote:
> This brings me to the next problem. Let's say that I provide a separate
> procedure Duplicate or Copy or Assign or whatever with the
> commit-or-rollback guarantees for some type (like Stack). Now, some of
> the types in my program will have ":=" for assignment, and some others
> will have the Copy procedure, but not ":=".
> I want to create a generic container or some other component that will
> copy things around internally. It has to use ":=" for some types (like
> Integer) and Copy for others (like Stack).
> In C++ I solve this problem (aside the fact that there is no problem in
> the first place) with template type traits or some other application of
> template specializations.
> What about Ada?
generic
type Object is limited private;
with procedure Deep_Copy (Left : in out Object; Right : Object) is <>;
package Container is
...
end Container;
-------------------------------
with Container;
generic
type Object is private;
package Specialized_Container is
procedure Deep_Copy (Left : in out Object; Right : Object);
pragma Inline (Deep_Copy);
package Copying_By_Assignment is new Container (Object);
end Specialized_Container;
-------------------------------
package body Specialized_Container is
procedure Deep_Copy (Left : in out Object; Right Object) is
begin
Left := Right;
end Deep_Copy;
end Specialized_Container;
Note also that your example is not much realistic. Transaction model is
expensive. One usually does not compose transactions. This means that
components of a container will be copied destructively, *after* necessary
memory allocation. Only the upper level will take care of a possibility to
roll things back. Thus it makes much sense to distinguish light-weight ":="
(which can't fail) and heavy-weight "Copy".
The container itself could be a red-black tree, which supports roll-backs
after mutations.
--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de
next prev parent reply other threads:[~2005-12-06 9:50 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-11-30 13:57 Controlled types and exception safety Maciej Sobczak
2005-11-30 15:06 ` Dmitry A. Kazakov
2005-11-30 16:19 ` Maciej Sobczak
2005-12-01 0:05 ` Stephen Leake
2005-12-01 9:21 ` Dmitry A. Kazakov
2005-12-01 10:46 ` Maciej Sobczak
2005-12-01 15:08 ` Dmitry A. Kazakov
2005-12-02 4:17 ` Randy Brukardt
2005-12-02 9:29 ` Maciej Sobczak
2005-12-02 18:12 ` tmoran
2005-12-02 19:15 ` Robert A Duff
2005-12-02 21:42 ` tmoran
2005-12-06 9:00 ` Maciej Sobczak
2005-12-06 9:50 ` Dmitry A. Kazakov [this message]
2005-12-06 18:34 ` Jeffrey R. Carter
2005-12-06 19:34 ` Randy Brukardt
2005-12-06 21:20 ` Dmitry A. Kazakov
2005-12-07 1:57 ` Jeffrey R. Carter
2005-12-08 0:50 ` Randy Brukardt
2005-12-08 19:37 ` Jeffrey R. Carter
2005-12-09 2:36 ` Randy Brukardt
2005-12-09 6:33 ` Jeffrey R. Carter
2005-12-09 20:35 ` Randy Brukardt
2005-12-10 7:53 ` Jeffrey R. Carter
2005-12-06 20:43 ` Dmitry A. Kazakov
2005-12-07 2:00 ` Jeffrey R. Carter
2005-12-07 10:01 ` Dmitry A. Kazakov
2005-12-02 23:21 ` Robert A Duff
2005-11-30 17:46 ` Jean-Pierre Rosen
2005-11-30 21:02 ` Jeffrey R. Carter
2005-11-30 22:06 ` Björn Persson
2005-11-30 23:52 ` Randy Brukardt
2005-12-01 5:26 ` Jeffrey R. Carter
2005-12-02 23:51 ` Robert A Duff
2005-12-06 11:41 ` Peter C. Chapin
2005-12-06 12:50 ` Jean-Pierre Rosen
2005-12-06 13:06 ` Dmitry A. Kazakov
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