Building Robust Object-Oriented Python Applications and Libraries/

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Solution: Create a Company's Logging System

Solution: Create a Company's Logging System

Learn how to implement the coded solution of a company logging system using the Singleton design pattern.

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Designing the Singleton logger

First, design the Singleton Logger class. This class will ensure that only one instance of the Logger exists throughout the application.

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Python 3.10.4
import threading
class Logger:
    _instance = None
    _lock = threading.Lock()  # Lock for thread-safe instantiation
    def __new__(cls):
        if cls._instance is None:
            with cls._lock:
                if cls._instance is None:
                    cls._instance = super().__new__(cls)
                    cls._instance.log_file = open("application_log.txt", "a")
        return cls._instance
    @staticmethod
    def get_instance():
        return Logger()

Code explanation

  • Line 4–5: Created the _instance variable that holds the singleton instance of the Logger class and a _lock variable containing threading.Lock() object for thread-safe instantiation.

  • Line 7–13: Created the __new__() function that will ensure that only one instance is created using _lock. If an instance exists, returns it; else, creates and assigns it.

  • Line 15–17: Created the ...

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