class Substitution extends stdClass
 {
  public $course_requirement; // The original degree requirement.
  public $course_list_substitutions; // The course(s) which are
  public $db_substitution_id; // the specific database id this object refers to.
  public $db_required_group_id;
  public $db_required_degree_id;
  //filling in for that requirement.
  public $bool_has_been_applied;
  public $bool_group_addition;
  public $faculty_id; // The faculty member that made the substitution.

  public $bool_outdated; // set to true if this is an outdated sub (for an old major or the like)
  public $remarks; // like a comment for the substitution.

  public $outdated_note; // will contain information about WHY this was outdated.
  public $assigned_to_degree_id = 0;
  public $school_id = 0;


  function __construct() 
   {

    $this->course_requirement = new Course();
    $this->course_list_substitutions = new CourseList();
    $this->bool_group_addition = false;
    $this->bool_outdated = false;
  }


  function to_string() 
   {
    $rtn = "";
    if ($this->bool_group_addition) 
     {
      $ga = "group addition ";
    }
    $rtn .= "Substitution: $ga " . $this->course_requirement->to_string() . " fulfilled by ";
    $rtn .= $this->course_list_substitutions->to_string() . "\n";
    $tcrgroup = new Group($this->course_requirement->assigned_to_group_id);
    $rtn .= "CR group: " . $tcrgroup->title . " CR semester num: " . $this->course_requirement->assigned_to_semester_num . "\n";
    $tsubgroup = new Group($this->course_list_substitutions->get_first()->assigned_to_group_id);
    $rtn .= "Sub group: " . $tsubgroup->title . " Sub semester num: " . $this->course_list_substitutions->get_first()->assigned_to_semester_num . "\n";


    return $rtn;
  }

}