Re: Function definitions - with clarification

["J-P. Rosen" <rosen@adalog.fr>]

Le 01/07/2014 10:58, Georg Bauhaus a écrit :
> On 30/06/14 19:55, Shark8 wrote:

> The parts local to the function just become inaccessible,
> but they exist, and they need to exist after return.
> 
> Consider, for example,
> 
>    type T0 is new Ada.Finalization.Controlled with record
>       A: Character := '#';
>    end record;
> 
>    function F return T0'Class
>    is
>       type T1 is new T0 with
>          record
>             N : Natural;
>          end record;
>    begin
>       declare
>          type Heap_Thing is access T1;
>          Result : Heap_Thing;
>       begin
>          Result := new T1'(Controlled with A => '*', N => 42);
>          return T0 (Result.all);
>       end;
>    end F;
> 
> If T0 has a component A : Character as indicated above,
> then the following statement should print '*':
> 
>    Put (F.A);
> 
> Things will be more interesting in case F returns
> an anonymous access T0'Class. (Seems a mine field, then,
> at least if T0 is derived from Finalization.Controlled.)
> 

You can still free the locally allocated object, what you return is a
copy of the T0 part of Result.all.

Proof: try changing it to limited_control...
-- 
J-P. Rosen
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