python-design-patterns/memento.py at main · daniele-salerno/python-design-patterns · GitHub

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from dataclasses import dataclass


@dataclass
class Memento:
    state: str


class Originator:
    def __init__(self, state):
        self.state = state

    def create_memento(self):
        return Memento(self.state)

    def restore_memento(self, memento: Memento):
        self.state = memento.state


class Caretaker:
    memento_list = []

    def save_state(self, state: Memento):
        self.memento_list.append(state)

    def restore(self, index: int):
        return self.memento_list[index]


if __name__ == '__main__':
    originator = Originator("initial state")
    caretaker = Caretaker()

    caretaker.save_state(originator.create_memento())
    print(f"Current state is {originator.state}")

    originator.state = "state 1"
    caretaker.save_state(originator.create_memento())
    print(f"Current state is {originator.state}")

    originator.state = "state 2"
    caretaker.save_state(originator.create_memento())
    print(f"Current state is {originator.state}")

    originator.restore_memento(caretaker.restore(1))
    print(f"Current state is {originator.state}")

    originator.restore_memento(caretaker.restore(0))
    print(f"Current state is {originator.state}")

    originator.restore_memento(caretaker.restore(2))
    print(f"Current state is {originator.state}")