package gradebook;

/**
 * Contains an individual grade.
 */
public abstract class Grade
{
   /**
    * The assignment the grade is for (it is contained in the gradebook's
    * list of assignments).
    */
   GradedItem assignment;
   /**
    * the points entered.
    */
   int points;
   /**
    * the total possible points.
    */
   int totalPoints;
   
   /**
    * Calulates percentage based on points and totalPoints.
    */
   /*@
    requires
      // points to be set and wont divide by zero
      (points != 0) && (totalPoints != 0);
    
    ensures
      (\result != 0);
    @*/
   abstract double percentage();
}