What is the Observer Pattern in Python?

Can you explain the Observer Pattern in Python?

Sure! The Observer Pattern is a behavioral design pattern that allows an object, known as the subject, to maintain a list of its dependents, called observers, and notify them of any state changes.

How do I implement it in Python?

You can implement it by creating a Subject class that maintains a list of observers and methods to attach, detach, and notify them. Each observer can implement an update method to receive notifications.

Can you show me a code example?

Absolutely! Here's a simple example:

class Subject:
    def __init__(self):
        self._observers = []

    def attach(self, observer):
        self._observers.append(observer)

    def detach(self, observer):
        self._observers.remove(observer)

    def notify(self):
        for observer in self._observers:
            observer.update()

class Observer:
    def update(self):
        print("Observer has been notified!")

subject = Subject()
observer1 = Observer()
subject.attach(observer1)
subject.notify()  # Output: Observer has been notified!

What are some real-world applications of the Observer Pattern?

It's commonly used in event handling systems, like GUI frameworks, where multiple components need to respond to events.