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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Forwarding declaration?
Newsgroups: comp.lang.ada
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Date: Fri, 1 Apr 2005 11:03:57 +0200
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Date: 2005-04-01T11:03:52+02:00
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On 1 Apr 2005 00:36:22 -0800, Andrew wrote:

> I have need of a forwarding declaration.  How do I do that in Ada?
> 
> --- example1 ---
> type Boob is record
>     Avar : A_Ptr;
> end record;
> type Boob_Ptr is access all Boob;
> 
> task type A(booby: Boob_Ptr) is
>    . . .
> end A;
> type A_Ptr is access all A;
> ------------------
> 
> compiler says (and I say) that A_Ptr is undefined for Boob.
> 
> Now if I could use a temporary placeholder for A_Ptr (a forwarding
> declaration) then the compiler and I would be happy.
> 
> --- example2 ---
> -- forwarding declaration
> temporary declaration of A_Ptr;
> 
> type Boob is record
>     Avar : A_Ptr;
> end record;
> type Boob_Ptr is access all Boob;
> 
> task type A(booby: Boob_Ptr) is
>    . . .
> end A;
> type A_Ptr is access all A;
> ------------------

type A; -- Forward declaration of A
type A_Ptr is access all A;

type Boob is record
  Avar : A_Ptr;
end record;
type Boob_Ptr is access all Boob;

task type A (booby : access Boob) is -- No need in pointers here
   ...
end A;

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