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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Copying rows in a two dimensional array.
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Date: Thu, 4 Feb 2010 10:10:06 +0100
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Date: 2010-02-04T10:10:06+01:00
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On Wed, 3 Feb 2010 20:13:20 -0800 (PST), Hibou57 (Yannick Duch�ne) wrote:

> On 1 f�v, 03:11, "Peter C. Chapin" <pcc482...@gmail.com> wrote:
>> Apparently the component type of an array needs to be fully constrained (which
>> again makes sense) yet I don't know the size
> That's what generics are made for.
> But you will have a single matrix type of a fixed size.

Generics per design are incapable to express that the thing is variable.
You cannot make a generic variable-dimension matrix, a generic string, or
for that matter even a generic number:

generic
   Value : WHAT?
package Integer is
   ...
end Integer;

That does not work.

> I you don't want a fixed size type, the best I will think about, would
> be to create an abstract matrix type which will be implemented on a
> one dimensional array. You could use slice in the implementation.

This does not work either, I mean at the user interface level, because
slice does not have a type. In Ada types system you cannot express "the
subtype S is a vector of the type M". Therefore making it abstract types
you will loose most of the comfort built-in arrays offer.

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