Re: better way?

["Nick Roberts" <nickroberts@callnetuk.com>]

I believe the orthodox answer to this would be that, since the two types
Inner_A_Thing_Type and Inner_B_Thing_Type are so closely related, the
definitions of these types and their primitive operations all belong
immediately within the one package. I illustrate below (with names changed
to hopefully increase clarity a tad).


package MacDonalds_Ultra is

   type Diner_Type is [tagged] [limited] private;
   type Meal_Type is [tagged] [limited] private;

   procedure Eat (Diner: in out Diner_Type; Meal: in Meal_Type['Class]);
   procedure Configure_Nutritional_Balance (Meal: in out Meal_Type; Diner:
in Diner_Type['Class]);

   ...

private
   ...

end MacDonalds_Ultra;


It doesn't seem immediately obvious to me why you wouldn't want to adopt
this approach, at least as a starting point. Sometimes it is useful to
define further packages which present essentially the same types and
operations in a different way. I think Ada.Text_IO shows a fairly good
example of the meaningful use of inner packages.

--
Nick Roberts
http://www.AdaOS.org


<tmoran@acm.org> wrote in message
news:16D06.22140$A06.845242@news1.frmt1.sfba.home.com...
> I'd like to do something like:
>   package Outer is
>
>     type Inner_A_Thing_Type;
>     type Inner_B_Thing_Type;
>
>     package Inner_A is
>       type Thing_Type is ...
>       procedre P(X : access Inner_B_Thing_Type);
>     end Inner_A;
>     subtype Inner_A_Thing_Type is Inner_A.Thing_Type;
>
>     package Inner_B is
>       type Thing_Type is ...
>       procedre Q(X : access Inner_A_Thing_Type);
>     end Inner_B;
>     subtype Inner_B_Thing_Type is Inner_B.Thing_Type;
>     ...
>   end Outer;
>
> but the "subtype" instead of "type" prevents it.  Suggestions?