Example package where a "protected" scope would be nice

foo.adb

package Foo is
   type A is abstract tagged null record;

   -- some functionality A provides
   procedure Bar (Object : A);
   
   -- some part of this functionality that depends
   -- on the specific child-classes of A
   -- this function should not be visible to other
   -- packages, but it has to be visible to packages
   -- that implement a child class of A.
   function Calculate (Object : A) return Integer is abstract;

end Foo;

package body Foo is
   procedure Bar (Object : A) is
      Var : Integer;
   begin
      -- do something
      -- ...
      -- let the specific child class define an implementation of this
      Var := Calculate (Object);
      -- continue doing something
      -- ...
   end Bar;

end Foo;