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From: Marcus Lauster <marcus.lauster@gmx.de>
Newsgroups: comp.lang.ada
Subject: Re: Programming by interface in Ada
Date: Wed, 13 Aug 2008 18:08:44 +0200
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Date: 2008-08-13T18:08:44+02:00
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Adam Beneschan schrieb:
> On Aug 13, 4:14 am, S�bastien Morand <seb.mor...@gmail.com> wrote:
[...]
>> The interface primitive it's yelling about should be SetObjet which is
>> correctly defined in the spec. So waht's the matter? It looks like the
>> MonObjetPtr (access all ObjInterface) is the real problem.
>>
>> How can I achieve this?
>>
>> Thanks by advance,
> 
> Well, I've found that if you change
> 
>   type MonObjetPtr is access all MonObjet;
> 
> to
> 
>   type MonObjetPtr is access all MonObjet'Class;
> 
> the error goes away.  There is no Ada reason why this should be so.  I
> think your program is legal and GNAT has a bug.  Maybe it's
> incorrectly applying a rule for anonymous-access parameters to your
> MonObjetPtr parameter.
> 

Maybe there is a reason. For me it seems to be ok, because an interface 
is a abstract type and therefore you aren't allowed to create an object. 
And as a consequence of this it seems that you also aren't allowed to 
create a direct reference to it. But you can have a reference to all 
objects wich are subsumed by this type.

I'm new to Ada if my toughts are going into the wrong direction correct 
me please.