Re: Self pointer in limited record

[Georg Bauhaus <bauhaus.rm.tsoh@maps.futureapps.de>]

Dmitry A. Kazakov wrote:

>> 2 - Nesting packages is an option, a distinguishing feature
>> of Ada IMO; a package nested inside a subprogram is a
>> simple solution to the life cycle problem of module style
>> objects.
> 
> Hmm, a subprogram has all properties of a package. So there is no obvious
> reason why nested package (except instances of generic packages, of
> course), might be useful there.

You can have two nested packages, or more. :-)

procedure run_a_farm is
   -- simplified

   type Sound is (Bow_Wow,
                  Cock_A_Doodle_Doo,
                  Moo,
                  Dinner_is_Ready,
                  Order);

   BARK : exception;

   package House is
      procedure Cook_Meal;
      procedure Eat;
      procedure Sleep;
      procedure Alarm;
   end House;

   package Barn is
      procedure Feed;
      procedure Milk;
      procedure Alarm;
   end Barn;

   task Events is
      entry Noise (Kind: Sound);
   private
      entry Call_Benjamin (Kind: Sound);
   end Events;

   package body House is separate;
   package body Barn is separate;
   -- Note: Both House and Barn can make Noise.
   -- Everyone can react to exceptional BARKing.

   task body Events is separate;

begin
   Events.Noise (Cock_A_Doodle_Doo);
end run_a_farm;