Deskriptorbasierter Modellfeld-Eigenschaftszugriff für dynamisches Typ-Casting

class TypedAttributeDescriptor:
    def __init__(self, field_name: str, target_type: type):
        self.field_name = field_name
        self.target_type = target_type
 
    def __get__(self, instance, owner=None):
        if instance is None:
            return self
        raw_val = instance.__dict__.get(self.field_name)
        if raw_val is None:
            return None
        return self.target_type(raw_val)
 
    def __set__(self, instance, value):
        instance.__dict__[self.field_name] = str(value) if value is not None else None