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From: "Jeffrey R. Carter" <spam.jrcarter.not@acm.nospam.org>
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Subject: Re: Another question about controlled types.
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Date: 2008-02-09T21:50:02+00:00
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Peter C. Chapin wrote:
> I'm using GNAT GPL 2007. I understand that Ada 2005 allows one to return 
> limited types from functions. Consider the following package 
> specification and body:
> 
> package Check is
>    type Some_Type is limited private;
>    function Make(I : Integer) return Some_Type;
> private
>    type Some_Type is
>       record
>          Component : Integer;
>       end record;
> end Check;

The full view is not limited.

> with Ada.Finalization;
> 
> package Check is
>    type Some_Type is limited private;
>    function Make(I : Integer) return Some_Type;
> private
>    type Some_Type is new Ada.Finalization.Limited_Controlled with
>       record
>          Component : Integer;
>       end record;
> end Check;

Here the full view is limited. That is the difference.

To return a limited value, you now need to either return an aggregate or use the 
extended return statement:

return Some_Type'(Ada.Finalization.Limited_Controlled with Component => I);

or

return Result : Some_Type do
    Result.Component := I;
end return;

See ARM 6.5.

-- 
Jeff Carter
"I soiled my armor, I was so scared."
Monty Python & the Holy Grail
71