CODESAMPLE

Mediator - Python

Mediator Python

The Mediator pattern defines an object that encapsulates how a set of objects interact. It promotes loose coupling by preventing objects from referring to each other explicitly, instead letting a mediator handle their communication. This allows you to vary the interactions independently of the interacting objects.

Here, ChatMediator is the mediator, coordinating messages between User objects. Each user only knows the mediator, not other users. The mediator implements send_message, which directs messages to the appropriate recipients based on their group membership. The use of abstract base classes (ABC, abstractmethod) and a central mediator class is consistent with Python’s support for both OOP and design patterns, enhancing maintainability and flexibility.

from abc import ABC, abstractmethod

class User(ABC):
    def __init__(self, name, mediator):
        self.name = name
        self.mediator = mediator

    @abstractmethod
    def send_message(self, message):
        pass

    def receive_message(self, message):
        print(f"{self.name} received: {message}")

class ConcreteUser(User):
    def send_message(self, message):
        self.mediator.send_message(self.name, message)

class Mediator(ABC):
    @abstractmethod
    def send_message(self, sender, message):
        pass

class ChatMediator(Mediator):
    def __init__(self):
        self.users = {}

    def add_user(self, user):
        self.users[user.name] = user

    def send_message(self, sender, message):
        for name, user in self.users.items():
            if name != sender:
                user.receive_message(f"{sender}: {message}")

if __name__ == '__main__':
    mediator = ChatMediator()
    user1 = ConcreteUser("Alice", mediator)
    user2 = ConcreteUser("Bob", mediator)
    user3 = ConcreteUser("Charlie", mediator)

    mediator.add_user(user1)
    mediator.add_user(user2)
    mediator.add_user(user3)

    user1.send_message("Hello everyone!")
    user2.send_message("Hi Alice!")
    user3.send_message("What's up?")