Proposed change to BC iterator parameters

[Simon Wright <simon@pushface.org>]

Martin Krischik <krischik@users.sourceforge.net>'s AdaCL
(http://adacl.sourceforge.net) includes changes to some of the Booch
Component iterators. For example,

   generic
      type Param_Type is private;
      with procedure Apply (Elem : in Item;
                            Param : in Param_Type;
                            OK : out Boolean);
   procedure Visit_With_In_Param (Using : in out Iterator'Class;
                                  Param : in Param_Type);
   --  Call Apply with a Parameter for each Item in the Container to
   --  which the iterator Using is bound. The iteration will terminate
   --  early if Apply sets OK to False.

Martin proposes

      type Param_Type (<>) is private;

but it occurs to me that the code ought to be

      type Param_Type (<>) is limited private;

As I understand it, this allows users much more freedom (you can even
use a tagged type provided you instantiate with Tagged_Type'Class).

But are there any downsides? (backward incompatibility being something
to for me to avoid!)

-- 
Simon Wright                               100% Ada, no bugs.