Have you ever created custom descriptors for objects or classes?

Yes, I have experience creating custom descriptors in Python. Descriptors are objects that manage access to attributes of other objects through the __get__, __set__, and __delete__ methods.

Here's an example of a simple descriptor that validates that the assigned value is a positive number:

class PositiveNumber:
    def __init__(self):
        self._value = 0

    def __get__(self, instance, owner):
        return self._value

    def __set__(self, instance, value):
        if value <= 0:
            raise ValueError("Value must be positive")
        self._value = value

class Product:
    price = PositiveNumber()

p = Product()
p.price = 100  # works
# p.price = -10  # will raise ValueError

This approach allows centralized control over attribute access and validation.