From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Ada 2005?
Date: Tue, 21 Dec 2004 18:12:55 +0100
Date: 2004-12-21T18:12:55+01:00 [thread overview]
Message-ID: <1vj2pp9437gal.1b1lyqe3o973k$.dlg@40tude.net> (raw)
In-Reply-To: m3652vy3uq.fsf@rigel.goldenthreadtech.com
On 21 Dec 2004 12:10:21 -0500, jayessay wrote:
> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
>
>> On 20 Dec 2004 18:44:14 -0500, jayessay wrote:
>>
>>> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
>>>
>>>> Copy is a friend, but they are not methods. C++ does not support multiple
>>>> dispatch.
>>>
>>> Yes, but to be clear, neither does Ada.
>>
>> Surprisingly, but it does:
>>
>> procedure Foo (X, Y : Some_Tagged_Type); -- This is legal
>>
>> Though it is very limited and cannot be counted as true multiple dispatch.
>
> Right. All the parameters in a dispatching call to such a case must
> resolve to the _same_ type (IIRC) and so it isn't "multiple" dispatch
> at all. True multiple dispatch occurs when such profiles can be
> called where the parameters resolve to different types (often not even
> in the same branch of the type hierarchy) and the correct method is
> dynamically invoked (1,2).
>
> 1. For an example of of multiple dispatch, see generic functions,
> method resolution and dispatch in CLOS:
>
> http://www.lispworks.com/reference/HyperSpec/Body/07_f.htm
> http://www.lispworks.com/reference/HyperSpec/Body/07_ff.htm
The problem with MD is not target method resolution, which is quite
trivial, but safety in presence of inheritance with combinatorial explosion
of target methods to override. I doubt that CLOS seriously approaches the
problem. Consider Ada. To provide MD on independent type hierarchies, you
should relax freezing rules for primitive operations. Doing so you have a
great problem of keeping the dispatching table consistent.
> 2. Overloading gives a kind of static version of this.
... being absolutely unsafe.
--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de
next prev parent reply other threads:[~2004-12-21 17:12 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-18 4:27 Ada 2005? conradwt
2004-12-18 8:08 ` Martin Dowie
2004-12-20 20:06 ` conradwt
2004-12-21 6:51 ` Martin Dowie
2004-12-18 8:47 ` christov
2004-12-19 3:28 ` Randy Brukardt
2004-12-19 19:11 ` christov
2004-12-19 22:07 ` Ada User Journal (was: Re: Ada 2005?) Dirk Craeynest
2004-12-19 22:34 ` Ada User Journal Florian Weimer
2004-12-20 9:19 ` Martin Krischik
2004-12-20 11:02 ` Florian Weimer
2004-12-20 12:22 ` Thomas Hühn
2004-12-27 13:16 ` Florian Weimer
2004-12-21 0:15 ` Ada 2005? David Botton
2004-12-18 8:51 ` Martin Krischik
2004-12-18 16:03 ` Dmitry A. Kazakov
2004-12-20 18:49 ` conradwt
2004-12-20 20:10 ` Dmitry A. Kazakov
2004-12-20 23:44 ` jayessay
2004-12-21 1:26 ` Alexander E. Kopilovich
2004-12-21 8:31 ` Dmitry A. Kazakov
2004-12-21 17:24 ` jayessay
2004-12-21 8:11 ` Dmitry A. Kazakov
2004-12-21 17:10 ` jayessay
2004-12-21 17:12 ` Dmitry A. Kazakov [this message]
2004-12-21 21:42 ` jayessay
2004-12-22 8:55 ` Dmitry A. Kazakov
2004-12-22 18:02 ` jayessay
2004-12-22 19:10 ` Dmitry A. Kazakov
2004-12-23 18:09 ` jayessay
2004-12-24 9:41 ` Dmitry A. Kazakov
2004-12-27 17:09 ` jayessay
2004-12-27 19:44 ` Dmitry A. Kazakov
2004-12-27 21:51 ` Georg Bauhaus
2004-12-28 9:56 ` Dmitry A. Kazakov
2004-12-28 17:56 ` jayessay
2004-12-28 17:48 ` jayessay
2004-12-28 17:36 ` jayessay
2004-12-21 8:33 ` Martin Krischik
2004-12-21 15:34 ` jimmaureenrogers
2004-12-21 15:53 ` Martin Krischik
2004-12-22 9:34 ` Larry Kilgallen
2004-12-22 11:01 ` Martin Krischik
2004-12-22 12:52 ` Larry Kilgallen
2004-12-22 16:38 ` Martin Krischik
2004-12-23 23:05 ` conradwt
2004-12-24 9:24 ` Pascal Obry
2004-12-24 9:59 ` Martin Krischik
2004-12-18 19:31 ` Jeffrey Carter
2004-12-20 18:55 ` conradwt
2004-12-20 23:53 ` Jeffrey Carter
2004-12-21 0:25 ` David Botton
2004-12-19 3:16 ` Brian May
2004-12-20 23:38 ` jayessay
2004-12-21 21:42 ` Brian May
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