Python structural patterns - proxy

proxy.py

# The proxy pattern allows us to perform some action, usually a check, before accessing an object.

from abc import ABC, abstractmethod

# define some interface
class Passwords(ABC):
    @abstractmethod
    def get_master_password(self):
        raise NotImplementedError


# and implementations of this
class SimonsPasswords(Passwords):
    def get_master_password(self):
        return "Wubba lubba dub dub"


class PasswordsProxy(Passwords):
    """ Run a check to see if the user is Simon.
        If the user is Simon then return password text,
        otherwise hide the password.
    """

    def __init__(self, user):
        self.user = user
        self.passwords = SimonsPasswords()

    def get_master_password(self):
        password = self.passwords.get_master_password()
        if self.user.lower() == "simon":
            return password
        else:
            return "*" * len(password)


proxy = PasswordsProxy(user="Bob")
print(proxy.get_master_password())  # *******************

proxy = PasswordsProxy(user="Simon")
print(proxy.get_master_password())  # Wubba lubba dub dub