Re: Proper program structure

[Brad Moore <brad.moore@shaw.ca>]

Sorry, need to make a correction to my last posting.

The automatic finalization would not have worked like I would have
wanted, since the vehicle_type is an access type, finalization would
have only occurred when the access type went out of scope (at program
finalization). To get the effect I was looking for would have required
garbage collection. To correct this, I make the Vehicle_Type a 
controlled record type containing an access to the internals.
I got rid of the inheritance, since it did not seem to be providing
much of a benefit.

Brad

i.e.

private with Ada.Finalization;
package Cars is
    type Vehicle_Type (<>) is limited private;
    function Construct return Vehicle_Type;
private
    use Ada.Finalization;
    type Car_Type;
    type Car_Access_Type is access Car_Type;
    type Vehicle_Type is new Limited_Controlled with
       record
          Car : Car_Access_Type;
       end record;
    overriding procedure Finalize (Vehicle : in out Vehicle_Type);
end Cars;

---------------------------

with Cars.Vehicle_Internal;
use Cars.Vehicle_Internal;
with Ada.Unchecked_Deallocation;
package body Cars is
    type Car_Type is
       record
          Internals : Vehicle_Internal_Type;
       end record;

    procedure Free_Car is new Ada.Unchecked_Deallocation
      (Object => Car_Type,
       Name => Car_Access_Type);

    function Construct return Vehicle_Type is
    begin
       return Vehicle : Vehicle_Type
       do
          Vehicle.Car :=
            new Car_Type'(Internals => Vehicle_Internal_Type'(Construct));
          return;
       end return;
    end Construct;

    overriding procedure Finalize (Vehicle : in out Vehicle_Type) is
    begin
       Free_Car (Vehicle.Car);
    end Finalize;

end Cars;