Dummy example of immutable class in python

inmutable_class.py

""" Dumb way to produce immutable instances in Python """


class ImmutablePerson(object):
    """ ... """

    __slots__ = ('name', 'dob')

    def __init__(self, name: str, dob: str):
        """ Only available at initialization """
        self.name = name
        self.dob = dob

    def __setattr__(self, key, value):
        """ Override to prevent mutability """
        if hasattr(self, key):
            raise ValueError(f'This instance {self} is immutable: unable to change {key} with value {value}')
        else:
            super(ImmutablePerson, self).__setattr__(key, value)

    @property
    def __dict__(self):
        return {s: getattr(self, s) for s in self.__slots__}

    def __repr__(self):
        return f'{self.__class__.__name__}({self.__dict__})'


if __name__ == '__main__':
    p = ImmutablePerson('Michelle', '1988-03-22')

    try:
        p.surname = 'Macron'
    except Exception as ex:
        print(f'{ex}')
    finally:
        print(f'{p}')

    try:
        p.name = 'Emmanuel'
    except Exception as ex:
        print(f'{ex}')
    finally:
        print(f'{p}')