#
# Base class to support checking constraints through metadata.
#
@dataclass
class CaseTalkBaseClass:
  def __post_init__(self):
    for fieldname, field in self.__dataclass_fields__.items():
      if 'required' in field.metadata:
        if field.metadata['required'] == True and getattr(self, fieldname) is none:
          raise ValueError('{fieldname} is Required')
  def __eq__(self, other):
    result = None
    for fieldname, field in self.__dataclass_fields__.items():
      if 'id' in field.metadata:
        if field.metadata['id'] == True:
          result = cmp(getattr(self, fieldname), getattr(other, fieldname))
          if result <> 0:
            break
    return result

@dataclass
class Student(CaseTalkBaseClass):
  firstname: str = field(metadata={'required'=True, 'id'=True})
  lastname: str = field(metadata={'required'=True, 'id'=True})
  buddy: Student
  type: Type = field(default="Student")