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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Imitation is the sincerest form of flattery
Date: Sun, 23 Mar 2003 09:51:55 +0100
Organization: At home
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Date: 2003-03-23T09:51:55+01:00
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Pascal Obry wrote:

> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
> 
>> > But how do you access element into this array, what would be done
>> > for:
>> > 
>> >    M : Sparse_Matix (1 .. 7, 1 .. 90);
>> > 
>> >    M (2, 6) := ...;
>> 
>> I have to prove an implementation for Set_Element, I suppose. When I
>> declare that Sparse_Matrix an array, I have to override all the abstract
>> methods of the universal array type might have. Set_Element is one of
>> them.
> 
> You mean that the compiler must generate a call to Set_Element/Get_Element
> for every reference to an array item, right ?

Surely

> So what you are looking for is a type with runtime support, a bit like
> Ada.Finalization API with the Initialize/Adjust/Finalize routines, right ?

There cannot be other mechanism I suppose. An universal array has some 
abstract primitive operations which has to be implemented. In case of 
built-in arrays, the implementeation is generated by the compiler. For 
user-defined ones, it is the programmer who implements them.

However, I am pretty aware that all unsolved problems with 
assignment/construction in Ada will inevitable show themselves for 
Set_Element.

-- 
Regards,
Dmitry A. Kazakov
www.dmitry-kazakov.de