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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Discriminant of a limited type object
Date: Wed, 28 Feb 2018 09:42:13 +0100
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Xref: reader02.eternal-september.org comp.lang.ada:50700
Date: 2018-02-28T09:42:13+01:00
List-Id: <comp.lang.ada>

On 28/02/2018 07:36, J-P. Rosen wrote:
> Le 27/02/2018 à 23:53, Dmitry A. Kazakov a écrit :
>>     A : T (1..N);
>> begin
>>     for Index in A'Range loop
>>        do-init of A (Index)
>>     end loop;
>>
>>          |
>>          V
>>
>>     Index : Positive := 1;
>>     function F return Element is
>>     begin
>>        Index := Index + 1;
>>        return do-init of A (Index - 1);
>>     end F;
>>     A : T (1..N) := (others => F)
> But this does not guarantee the order of components. I'd rather write
> (changing do_init to a function):
>     function Init_All (Size : Integer) return T is
>     begin
>        if Size = 1 then
>           return (1 => do_init)
>        else
>           return do_init & Init_All (size - 1);
>        end if;
>     end;
> 
>     A : T := Init_All (N);

You are right, I forgot about the arbitrary order of initialization!

It was mad already. Recursion adds a new level of madness into it. 
(Provided GNAT would generate working the code at all. It has issues 
with limited return in much simpler cases.)

But it is still arbitrary order in "&" arguments. Though do_init could 
take as an argument N - Size + 1 in order to determine the element's 
index, any other external state is not guaranteed. E.g. initialization 
of A (I + 1) cannot depend on initialization of A (I).

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