Validation of types, private attributes implementation

from typing import Any, Callable


class Ensure:

    def __init__(self, validate: Callable[[str], None], doc: str=None):
        self.validate = validate
        self.doc = doc


def is_not_empty_str(name: str, value: str):
    print('Validating value: %s' % name)

    if not isinstance(value, str):
        raise ValueError('%s must be string' % name)

    if not bool(value):
        raise ValueError('%s may not be empty' % name)


def do_ensure(Class):
    def make_property(name: str, attribute: Any) -> Class:
        privatName = "__" + name

        def getter(self):
            print("Getter for attribute: %s" % name)
            return getattr(self, privatName)

        def setter(self, value: Any):
            print("Getter for attribute: %s" % name)
            attribute.validate(name, value)
            setattr(self, privatName, value)

        return property(getter, setter, doc=attribute.doc)

    for name, attribute in Class.__dict__.items():
        if isinstance(attribute, Ensure):
            setattr(Class, name, make_property(name, attribute))

    return Class


@do_ensure
class Book:

    book_name = Ensure(is_not_empty_str)
    author = Ensure(is_not_empty_str)

    def __init__(self, book_name: str, author: str):
        self.book_name = book_name
        self.author = author


___________________________________________________________
Input:
>> book = Book('title', 'author')

Output:
>> Setter for attribute: book_name
>> Validating value: book_name
>> Setter for attribute: author
>> Validating value: author