"Ted Dennison" <dennison@telepath.com> a �crit dans le message news: 95rpj5$gq7$1@nnrp1.deja.com...
> I have to admit I'm a little unclear as to what nasty things could
> happen to me if I were allowed to declare a derived tagged type at a
> lower scope level than their parent type.
OK, let's go:

package body Pack is
   type Parent is tagged ...;
   procedure Proc (X : Parent) is ... end Proc;

   type Ptr is access Parent'Class;
   V : Ptr;

   procedure P is
      type Child is new Parent with...;
      procedure Proc (X : Child) is... end Proc;
   begin
      V := new Child;
   end P;

begin
   P;
-- Now, V.all points to an object of type P.Child
-- We can call Proc (V.all) which will result in a dispatching call to P.Proc, but P is out of scope at this point !!!