Python object that monitors changes in objects

Title: Monitoring Changes in Python Objects with Observers
Introduction:
In Python, you can implement a design pattern known as the Observer pattern to monitor changes in objects. The Observer pattern allows you to define a one-to-many dependency between objects so that when one object (the subject) changes state, all its dependents (observers) are notified and updated automatically. In this tutorial, we'll walk you through how to implement this pattern to monitor changes in Python objects.
Table of Contents:
The Observer pattern consists of the following key components:
Subject: The object that is being observed. It maintains a list of its dependents (observers) and notifies them when its state changes.
Observer: The objects that are interested in monitoring the state changes of the subject. They register with the subject to receive notifications.
Notification: When the state of the subject changes, it sends notifications to all registered observers, informing them about the change.
To implement the Observer pattern in Python, you can follow these steps:
Create a Subject class that maintains a list of observers and provides methods to attach, detach, and notify observers.
Create an Observer class that defines the update method, which will be called when the subject notifies it.
ConcreteSubject: A subclass of the Subject class that represents the object you want to monitor.
ConcreteObserver: A subclass of the Observer class that specifies what to do when it's notified of changes in the subject.
In this example, we'll create a simplified monitoring system for tracking changes in a stock price.
In this example, the Stock class is the ConcreteSubject, and the PriceWatcher class is the ConcreteObserver. When the stock price changes, it notifies all registered observers, and they can take appropriate action, such as printing the new price.
By using the Observer pattern, you can easily monitor changes in objects in a flexible and maintainable way. This pattern is particularly useful in event-driven systems, GUI applications, and real-time monitoring scenarios.
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