Assigning a "subclass" instance to a "superclass" variable

[deuteros <deuteros@xrs.net>]

I'm still trying to understand how Ada does object orientation. In Java I could
do this: 

Class Animal
{
  String color;

  public Animal(String color)
  {
    	this.color = color;
  }
}

Class Dog extends Animal
{
  public Dog(String color)
  {
    	super(color);
  }
}

So in Ada I'm trying to achieve something similar with my Statement
package: 

package Statements is

   type Statement is abstract tagged
      record
         tokens : Vector;
         executedtokens : Vector;
      end record;
   
   type Statement_Access is access all Statement'Class;
   
   function execute(skip: in Boolean; S: in Statement) return Integer is abstract;

end Statements;

So when I create a child of Statement, how to I set up the .ads file?