Strongly private property does not work in Python3 through __property, tell me?

Question:

I'm learning Python3, got to encapsulation and here I can't understand. If I understood correctly, then the __ of the class property indicates that you cannot directly access this method through obj.__variable , right?

But I can’t make the property private, I tried it through __init__() , and just create __ in the class body.

Through the setter-getter it works fine, but directly through obj.__variable they can change and read the value.

Please tell me where I went wrong? I do not want to go further without understanding this important topic.

The code:

# Создаем класс Auto
class Auto:
    # Инициализация
    def __init__(self):
        self.__number = ""
        print("Создали класс Auto")

    # Свойства
    # Номер автомобиля, сильно приватное свойство, т.к. __ префикс и обратиться напрямую нельзя через obj.__свойство
    #__number = ""

    # Сеттер
    def set_number(self, number):
        # Валидация данных
        if len(number) in [7, 8]:
            self.__number = number
        else:
            print("Номер автомобиля неправильный, задайте 7 или 8 цифр.")
    # Геттер
    def get_number(self):
        return self.__number

# Создаем объект Audi
audi = Auto()

# Задаем значение audi.__number через сеттер и считываем через геттер
audi.set_number("A777SD77")
print(audi.get_number())

# Пытаемся задать или прочитать свойство с сильной приватностью __number напрямую - нельзя, т.к. сильно приватное
audi.__number = "L123OX23"
print(audi.__number)

# Считываем значение изначального __number через геттер, а не созданного извне _Auto__number, оно не изменилось
print(audi.get_number())

Result:

Создали класс Auto
A777SD77
L123OX23

Process finished with exit code 0

Answer:

This is because on the penultimate line ( audi.__number = … ) you are creating a new attribute from the outside , the exact name of which is __number .
The __number attribute you created from inside the class actually gets the name _Auto__number , which is precisely the privacy indicator.

Private attributes are not a hard and fast rule, just a convention. If for some reason you need to access such an attribute, then the programmer can do it.

More details: https://docs.python.org/3/tutorial/classes.html#private-variables