From: Michael Erdmann <michael.erdmann@snafu.de>
To: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Q: Endless loop by dispatching
Date: Fri, 11 Jul 2003 17:07:52 +0200
Date: 2003-07-11T17:07:52+02:00 [thread overview]
Message-ID: <3F0ED2C8.6080409@snafu.de> (raw)
In-Reply-To: <uu0tgv8ru6be67limc43p4itiu46s4ac19@4ax.com>
Dmitry A. Kazakov wrote:
>>Does any body know, what this loop causes?! I am not sure
>>if this is a bug or simply i missed the point.
>
>
> Serialize is class-wide and a view conversion does not change the
> tag..I.e. you have a re-dispatching case. Re-dispatching is a
> dangerous thing. [I would like it removed from Ada]
>
> So Serialize re-dispatches to B.Write which again calls Serialize.
> From design point of view, one should never call class-wide routines
> from specific ones, this warranties that dispatch happens only once.
>
> I suppose that you want sort of procedure expansion instead of
> complete overriding, if so, then you should explicitly call parent's
> Write, similarly as one does it for Initialize/Finalize:
>
Unfortuantly this was not the complete code. The Serialize was itended
to do a more complex job, which i have to replicate any where i want
to serialize an object. The original serialize code looks some what
like this:
procedure Serialize( This : in Object'Class ) is
........
a := next(Attributes(This'Tag))
while a /= null loop
Write( this.all, a.id );
a := next(....);
end loop;
end;
The procedure write is a procedures which writes out a selected
attribute of an object. The procedure Serialize the complete
object. I would have been great when i could write something
like this in ada:
procedure Serialize( This : in Object'Class ) is
Serialize( Super( This ) );
a := next(Attributes(This'Tag))
while a /= null loop
Write( this.all, a.id );
a := next(....);
end loop;
end;
I think something like this does not exist in Ada!?
> package body B is
> ...
> procedure Write (This : in Object) is
> begin
> -- A.Serialize( A.Object( This ) );
> A.Write (A.Object (This)); -- Write parent's things
> Put_Line( "Q =" & Natural'Image(This.Q));
> end Write;
>
> BTW, why do not you use Ada.Streams? It is for things like this.
I fact i am using Ada.Stream, but as i have written above the code was
simply a consended version.
>
> ---
> Regards,
> Dmitry Kazakov
> www.dmitry-kazakov.de
next prev parent reply other threads:[~2003-07-11 15:07 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-07-11 8:22 Q: Endless loop by dispatching Michael Erdmann
2003-07-11 9:46 ` Jean-Pierre Rosen
2003-07-11 15:19 ` Michael Erdmann
2003-07-11 10:01 ` Q: " Dmitry A. Kazakov
2003-07-11 15:07 ` Michael Erdmann [this message]
2003-07-12 1:41 ` Jeffrey Carter
2003-07-14 8:48 ` Dmitry A. Kazakov
2003-07-14 18:38 ` Randy Brukardt
2003-07-15 8:47 ` Dmitry A. Kazakov
2003-07-15 17:23 ` Randy Brukardt
2003-07-16 8:08 ` Dmitry A. Kazakov
2003-07-16 17:44 ` Robert I. Eachus
2003-07-17 1:57 ` Robert A Duff
2003-07-18 9:10 ` Dale Stanbrough
2003-07-18 20:26 ` Robert I. Eachus
2003-07-18 21:35 ` tmoran
2003-07-19 0:25 ` Robert I. Eachus
2003-07-19 2:30 ` tmoran
2003-07-19 5:48 ` Robert I. Eachus
2003-07-21 8:38 ` Dmitry A. Kazakov
2003-07-21 10:08 ` Robert I. Eachus
2003-07-21 13:21 ` Dmitry A. Kazakov
2003-07-21 18:51 ` Robert I. Eachus
2003-07-22 7:41 ` Dmitry A. Kazakov
2003-07-22 10:36 ` Lutz Donnerhacke
2003-07-22 12:11 ` Dmitry A. Kazakov
2003-07-22 12:18 ` Lutz Donnerhacke
2003-07-22 14:46 ` Dmitry A. Kazakov
2003-07-22 15:11 ` Lutz Donnerhacke
2003-07-23 8:12 ` Dmitry A. Kazakov
2003-07-19 14:44 ` Chad R. Meiners
2003-07-20 12:36 ` Robert I. Eachus
2003-07-11 16:27 ` T. Kurt Bond
2003-07-12 8:37 ` Michael Erdmann
2003-07-15 7:11 ` Kenneth Almquist
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