singleton.py

"""
        CopyLeft 2021 Michael Rouves

        This file is part of Pygame-DoodleJump.
        Pygame-DoodleJump is free software: you can redistribute it and/or modify
        it under the terms of the GNU Affero General Public License as published by
        the Free Software Foundation, either version 3 of the License, or
        (at your option) any later version.

        Pygame-DoodleJump is distributed in the hope that it will be useful,
        but WITHOUT ANY WARRANTY; without even the implied warranty of
        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
        GNU Affero General Public License for more details.

        You should have received a copy of the GNU Affero General Public License
        along with Pygame-DoodleJump. If not, see <https://www.gnu.org/licenses/>.
"""


class Singleton:
    """
        Singleton pattern.
        Overload only class that must have one instance.
        Stores the instance in a static variable: Class.instance
        (Check Singleton design pattern for more info)
    """

    def __new__(cls, *args, **kwargs):
        if not hasattr(cls, 'instance'):
            cls.instance = super(Singleton, cls).__new__(cls)
        return cls.instance