Build a Chat RoomStep 5 of 5

Centralized Policy: Banned Words

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Step 5: Centralized Policy: Banned Words

Because every message flows through the mediator, the room is the perfect place to enforce policy in one location. Add a banned-words filter so a blocked message is stopped once, for everyone, instead of being checked in many places.

The room stores a list of banned words (starting empty). Implement set_banned_words(words) to replace that list with the given words. Then update broadcast so that if the message contains any banned word (as a substring), it is delivered to no one; otherwise it is delivered as before to every user except the sender.

A clean message goes through normally; a message containing a banned word reaches nobody.

Hints
Starter code
class User:
    def __init__(self, name):
        self.name = name
        self.inbox = []
        self.room = None

    def send(self, message):
        self.room.broadcast(self, message)


class ChatRoom:
    def __init__(self):
        self.users = []
        self.banned_words = []

    def register(self, user):
        self.users.append(user)
        user.room = self

    def set_banned_words(self, words):
        """Replace the room's banned-words list with the given words."""
        # TODO: store a copy of words as self.banned_words
        pass

    def broadcast(self, sender, message):
        # TODO: if message contains any banned word, deliver to no one
        for user in self.users:
            if user is not sender:
                user.inbox.append(message)

    def send_private(self, sender, target_name, message):
        for user in self.users:
            if user.name == target_name:
                user.inbox.append(message)
                return

    def unregister(self, user):
        if user in self.users:
            self.users.remove(user)
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