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Date: Fri, 29 Jun 2007 11:42:56 +0200
From: Georg Bauhaus <bauhaus@futureapps.de>
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Subject: Re: Bus error
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Date: 2007-06-29T11:39:36+02:00
List-Id: <comp.lang.ada>

Maciej Sobczak wrote:
>
> Yes, or even stricter:
> 
>     with Ada.Finalization; use Ada;
>     package P is
>         type T (<>) is limited private;
>     private
>         type T is new Finalization.Limited_Controlled with ...;
>     end P;
> 
> which prevents uninitialized objects.

Uhm, it prevents uninitialized objects that cannot otherwise
have default initialisation (e.g. from function calls whose
results are assigned to components), or initialisation via Initialize.
Such as records that need their components initialised with
values known only at run time *and* defined at library level etc.

In a less flat architecture (which dismisses the possibilites of
nested block structure :), consider a plain limited type T in some
suitably nested block:


procedure Operate_System_95 is


    type External_State is new Natural;

    outside: External_State;
    

    
    package P is

        type T is limited private;

    private
        
        type Void is null record;
    
        function Constructor(Object: access T) return Void;
        
        type T is limited record
            hook: Void := Constructor(T'access);
            count: Natural;
        end record;

    end P;

    package body P is
    
        function Constructor(Object: access T) return Void is
        begin
            Object.count := Natural(outside);
            return (null record);
        end Constructor;
        
    end P;

    V: P.T;  --  initialisation via Constructor is guaranteed

begin
    null;
end Operate_System_95;