How to create a singleton in Python?

Better Stack Team
Updated on February 17, 2023

The singleton pattern is a software design pattern that restricts the instantiation of a class to a singular instance.

Using metaclass

In Python, there are multiple ways to do that but the most effective is using metaclasses.

class Singleton(type):
    _instances = {}
    def __call__(cls, *args, **kwargs):
        if cls not in cls._instances:
            cls._instances[cls] = super(Singleton, cls).__call__(*args, **kwargs)
        return cls._instances[cls]

class Logger(metaclass=Singleton):

In the example above, the Logger class is a singleton - every instance of the Logger will be the same. There will always be only one Logger and all Logger objects will refer to that one Logger.

Make your mark

Join the writer's program

Are you a developer and love writing and sharing your knowledge with the world? Join our guest writing program and get paid for writing amazing technical guides. We'll get them to the right readers that will appreciate them.

Write for us
Writer of the month
Marin Bezhanov
Marin is a software engineer and architect with a broad range of experience working...
Build on top of Better Stack

Write a script, app or project on top of Better Stack and share it with the world. Make a public repository and share it with us at our email.

or submit a pull request and help us build better products for everyone.

See the full list of amazing projects on github