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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Preventing type extensions
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Date: Tue, 21 Sep 2010 18:25:07 +0200
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Date: 2010-09-21T18:25:05+02:00
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On Tue, 21 Sep 2010 07:44:51 -0700 (PDT), Cyrille wrote:

> On Sep 21, 4:19�pm, "Dmitry A. Kazakov" <mail...@dmitry-kazakov.de>
> wrote:
>>
>> It is a distinction between a member and a set where it belongs to. These
>> are not equivalent.
> 
> not sure what you call "set" in this context... probably not the
> container of the same name ;-)

Set as in mathematics. A class wide type has values corresponding to the
values of types from the closure set, the closure set is build upon the
relation <: (derived from).

>>  Furthermore a type may be member of more than one
>> classes (sets of types). Also an operation may be primitive in more than
>> one class (AKA multiple dispatch).
> 
> in Ada? can you show an example?

Both MI and MD partially exist in Ada.

MI is restricted to interfaces.

MD is restricted to diagonal multi-methods, e.g:

   type T is tagged ...;
   procedure MD_operation (X, Y : T);

>>> A horse is an animal...
>>
>> But animal is not necessary a horse.
> 
> right. so?

horse /= animal

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de