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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Why constructing functions is a mess [was Language lawyer
 question: task activation
Newsgroups: comp.lang.ada
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Date: Mon, 2 Mar 2009 18:46:43 +0100
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Date: 2009-03-02T18:46:47+01:00
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On Mon, 02 Mar 2009 17:13:09 +0100, Georg Bauhaus wrote:

> Dmitry A. Kazakov schrieb:
> 
>> A derived type works fine:
>> 
>>    type My_Plant is new Power_Plant with null record;
>>    function Create return My_Plant is
>>    begin
>>       return (Power_Plant'(Create ("my plant")) with null record);
>>    end Create;
> 
>> Now, the point is that this model of construction does not work with
>> abstract types because of fundamental reasons. It is not (<>) which is
>> broken, but the construction model.
> 
> OK, got your point, sorry for being so dense.

No, you still have not. The problem is that the idea of constructing
functions replacing constructors is broken. The example I presented is just
one consequence of this flaw.

> Should the following work for unconstrained abstract Power_Plant?
> (some day, e.g.
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34507 )

It is not a compiler bug. It is a language bug. Besides, I have GNAT Pro.

> Would you consider dropping a note on AI05-067 to the ARG list?

Thank you for illustrating my point. This AI perfectly illustrates were
assumptions like 2+2=5 lead:

COMING SOON: !! Mutating objects and Spider-Man !!

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