Re: Question about OO programming in Ada

[Ludovic Brenta <ludovic.brenta@insalien.org>]

Dmitry A. Kazakov <mailbox@dmitry-kazakov.de> writes:

> On 03 Dec 2003 10:29:17 +0100, Pascal Obry <p.obry@wanadoo.fr> wrote:
> 
> >
> >Dmitry A. Kazakov <mailbox@dmitry-kazakov.de> writes:
> >
> >> All controlled objects allocated by the allocator new, being not
> >> explicity destroyed using Unchecked_Deallocation, will be destroyed
> >> upon finalization of the access type.
> >
> >There is no magic done by Finalize here! Finalize gives a chance to the
> >component implementer to do the memory deallocation for the end user. That's
> >all.
> 
> Yes, you are right. Controlled objects will be finalized, but the
> memory might be not reclaimed. At least, it seems that ARM does not
> require that.

I am confused.  I thought that the storage would be reclaimed when the
access type went out of scope, but I tested it with GNAT 3.15p and it
isn't.  Granted, the ARM doesn't seem to require it, but GNAT has the
following in its reference manual:

    *53*.  The manner of choosing a storage pool for an access type
    when `Storage_Pool' is not specified for the type.  See 13.11(17).

    There are 3 different standard pools used by the compiler when
    `Storage_Pool' is not specified depending whether the type is
    local to a subprogram or defined at the library level and whether
    `Storage_Size'is specified or not.  See documentation in the
    runtime library units `System.Pool_Global', `System.Pool_Size' and
    `System.Pool_Local' in files `s-poosiz.ads', `s-pooglo.ads' and
    `s-pooloc.ads' for full details on the default pools used.

And in s-pooloc.ads it says:

   ----------------------------
   -- Unbounded_Reclaim_Pool --
   ----------------------------

   --  Allocation strategy:

   --    Call to malloc/free for each Allocate/Deallocate
   --    no user specifiable size
   --    Space of allocated objects is reclaimed at pool finalization
   --    Manages a list of allocated objects

   --  Default pool in the compiler for access types locally declared

   type Unbounded_Reclaim_Pool is new [...]

I tried to run a test program in gnatgdb but couldn't check what the
storage pool actually was.  Would anyone care to shed some light on
this?  Now I'm really curious.

-- 
Ludovic Brenta.