Re: Limited_Controlled types as 'out' arguments

["Randy Brukardt" <randy@rrsoftware.com>]

"Lutz Donnerhacke" <lutz@iks-jena.de> wrote in message
news:slrnbihtb3.2j7.lutz@taranis.iks-jena.de...
...
> Results in:
> Initializing 134630800(0)
> Initializing 134630816(1)
> Setting from 134630816(1)
> Setting o1   134630800(0)
> Setting o2   134630800(0)
> Finalizing   134630800(0)
> raised PROGRAM_ERROR : t1.adb:14
> Finalizing   134630816(1)
>
> I'am mad?

Yes. :-)

Finalize routines always have to be written to work on an already finalized
object. There are variety of ways for extra Finalize calls to occur even
without any explicit ones. So your Finalize needs to be something like:

   procedure Finalize(o : in out Test) is
   begin
      if o.a /= null then
        Debug("Finalizing  ", o.a);
        Free(o.a);
      -- else already finalized.
      end if;
   end Finalize;

Otherwise, you're freeing an already freed object. This is discussed in the
AARM:
    http://www.adaic.org/standards/95aarm/html/AA-7-6-1.html
See the note at paragraph 24 and the following discussion.

                        Randy.