Singleton¶

• The singleton pattern is a software design pattern that restricts the instantiation of a class to one "single" instance.
• This is useful when exactly one object is needed to coordinate actions across the system.

Common use cases of singleton pattern¶

• Configuration Settings
• Logging
• Caching and thread pool
• Database connections

Example implementation of singleton pattern¶

• Let's implement the database connection with singleton pattern

class DB:
    __connection = None

    @classmethod
    def connect(cls):
        if not cls.__connection:
            print('Establishing connection...')
            cls.__connection = ...
        return cls.__connection


if __name__ == '__main__':
    connection1 = DB.connect()
    connection2 = DB.connect()

In the above code, we have called DB.connect() twice. but, it will be create only one database connection.

References:¶

• https://en.wikipedia.org/wiki/Singleton_pattern