Python call private parent method

I have a parent class writer that i define like this:

class writer:
    def __init__(self, file) -> None:
        self.file = file

    def write_content(self, content):
        self.file.write(content)
        self.__write_custom_footer()

    def __write_custom_footer():
        """
           Need to keep it private
        """
        # Do something

And I use this class as a parent this class:

class greetings_writer(writer):
    def __init__(self, file) -> None:
        super().__init__(file)

    def write_greetings(self):
        self.file.write("Hello")
        self.__write_custom_footer()

My problem append when i try to call the self.__write_custom_footer().

I get and AttributeError greetings_writer' object has no attribute '_greetings_writer__write_custom_footer'

For me this is due to the fact that `__write_custom_footer“is in private in the Parent class but how can I make it usable for all the child component but not from anything other?

I also tried with super().__write_custom_footer() and I got a simillar error

>Solution :

Your issue is indeed because of Python’s name mangling for private methods, which renames __write_custom_footer in writer to _writer__write_custom_footer. This makes it inaccessible directly from greetings_writer, as it’s looking for _greetings_writer__write_custom_footer.

To make the method accessible to child classes but still prevent direct access from outside, you can use a single underscore (_write_custom_footer) instead of double underscores. In Python, a single underscore conventionally signals that a method is intended for internal use (like "protected" in other languages) but is still accessible to subclasses:

class Writer:
    def __init__(self, file) -> None:
        self.file = file

    def write_content(self, content):
        self.file.write(content)
        self._write_custom_footer()  # Changed to single underscore

    def _write_custom_footer(self):
        # Do something (keep this "protected" by convention)
        pass

Now, in your greetings_writer, you can call _write_custom_footer() directly:

class GreetingsWriter(Writer):
    def __init__(self, file) -> None:
        super().__init__(file)

    def write_greetings(self):
        self.file.write("Hello")
        self._write_custom_footer()  # Accessible due to single underscore

Using a single underscore keeps the method "protected" by convention, meaning it’s intended for internal use, while still making it accessible to child classes.