I have following classes:

from abc import ABC, abstractmethod


class VarCharType(str, ABC):
    def __init__(self, value):
        self._validate_length(value)

    def _validate_length(self, value: str):
        if not self._min_length <= len(value) <= self._max_length:
            raise TypeError(f'Length must be between {self._min_length} and {self._max_length}')

    @property
    @abstractmethod
    def _min_length(self) -> int:
        pass

    @property
    @abstractmethod
    def _max_length(self) -> int:
        pass


class GivenName(VarCharType):
    _MIN_LENGTH = 1
    _MAX_LENGTH = 255

    @property
    def _min_length(self) -> int:
        return self._MIN_LENGTH

    @property
    def _max_length(self) -> int:
        return self._MAX_LENGTH


class FamilyName(VarCharType):
    ...

To test my code I decided to create random values of FamilyName and GivenName through a Mother pattern. Something like that:

class GivenNameMother:
    def random_max(self) -> GivenName:
        return GivenName(''.join(random.choices(string.ascii_uppercase, k=255)))
    
    def random_min(self) -> GivenName:
        return GivenName(''.join(random.choices(string.ascii_uppercase, k=1)))

class FamilyNameMother:
    def random_max(self) -> FamilyName:
        return FamilyName(''.join(random.choices(string.ascii_uppercase, k=255)))
    
    def random_min(self) -> FamilyName:
        return FamilyName(''.join(random.choices(string.ascii_uppercase, k=1)))

Previous implementation have several problems:

• If GivenName changes Max or Min length I must change the Mother class. I have some doubts if it is a feature or a problem.
• For each VarCharType children classes I need to create a mother class with more or less the same code. The problem is in some moment I want to test with utf-8 characters I should change all mother classes.

I tried several solutions but are very dirty and I do not like it.

What would be the best solution? It is a requirement avoiding typing with Any from typing package.

Thanks!