A Python singleton

singelton.py

import logging

LOG = logging.getLogger(__name__)


class Singleton:
    """Abstract class that forces only one instance of the child to be created."""

    #: Singleton controller; True if an instance of this class has already been created
    created = False

    def __init__(self):
        if self.created:
            error = PermissionError(f"Only one '{self.__class__.__name__}' can be created!")
            LOG.exception(error.args[0], exc_info=error)  # args[0] is the message
            raise error
        self.__create()

    @classmethod
    def __create(cls):
        """Set this class to 'created' status."""
        cls.created = True