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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Operation can be dispatching in only one type
Newsgroups: comp.lang.ada
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Date: Mon, 16 Nov 2009 21:32:46 +0100
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On Mon, 16 Nov 2009 21:28:00 +0100, Dmitry A. Kazakov wrote:

> At the same time the case represented by "diagonal" dispatch is very
> important in other situations, like parallel hierarchies of types. E.g.
> when we wanted to force a new instance from B'Class for each new instance
> from A'Class. But again that enforcement shall be static. BTW, it is not
> multiple dispatch. Technically this is rather single dispatch where the
> tuple of types (A, B) is considered as root of some class of tuples, in
> which (A1, B1), (A2, B2) are instances. Presently we have nothing in the
> language to handle this (except the jack-of-all-trades, generics). It would
> be interesting to speculate how tuples can be supported in Ada, especially
> their flattening in the arguments lists, and using tuples as multiple
> results of a function.

I forgot to say, that in this case illegal combinations like A1, B2 are
statically illegal, because there would be no tuple (A1, B2) declared.

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