Re: A good program that not compile

[Victor Porton <porton@narod.ru>]

Now it works! 100%

No need to change Ada standard.

The latest listing follows:

-- my.ads
with Ada.Finalization;

package My is

   type Abstract_Handle is abstract new Ada.Finalization.Limited_Controlled with
      record
         Handle: Integer;
      end record;

   function Obtain_Handle(Object: Abstract_Handle) return Integer is abstract;

   overriding procedure Initialize(Object: in out Abstract_Handle);

   type File_Handle is new Abstract_Handle with null record;

   overriding function Obtain_Handle(Object: File_Handle) return Integer;

end My;

-- my.adb
package body My is

   overriding procedure Initialize(Object: in out Abstract_Handle) is
   begin
      Object.Handle := Obtain_Handle(Abstract_Handle'Class(Object));
   end;

   overriding function Obtain_Handle(Object: File_Handle) return Integer is
   begin
      return 123; -- Suppose 123 is a file handle, for an example
   end;

end My;

-- main.adb
with My;
with Ada.Text_IO;

procedure Main is
   X: My.File_Handle;
begin
   Ada.Text_IO.Put_Line(Integer'Image(X.Handle));
end;


-- 
Victor Porton - http://portonvictor.org