client.py

# pylint: disable=too-few-public-methods
"The State Use Case Example"
from abc import ABCMeta, abstractmethod


class Context():
    "This is the object whose behavior will change"

    def __init__(self):

        self.state_handles = [
            Started(),
            Running(),
            Finished()
        ]
        self._handle = iter(self.state_handles)

    def request(self):
        "Each time the request is called, a new class will handle it"
        try:
            self._handle.__next__()()
        except StopIteration:
            # resetting so it loops
            self._handle = iter(self.state_handles)


class IState(metaclass=ABCMeta):
    "A State Interface"

    @staticmethod
    @abstractmethod
    def __call__():
        "Set the default method"


class Started(IState):
    "A ConcreteState Subclass"

    @staticmethod
    def method():
        "A task of this class"
        print("Task Started")

    __call__ = method


class Running(IState):
    "A ConcreteState Subclass"

    @staticmethod
    def method():
        "A task of this class"
        print("Task Running")

    __call__ = method


class Finished(IState):
    "A ConcreteState Subclass"

    @staticmethod
    def method():
        "A task of this class"
        print("Task Finished")

    __call__ = method


# The Client
CONTEXT = Context()
CONTEXT.request()
CONTEXT.request()
CONTEXT.request()
CONTEXT.request()
CONTEXT.request()
CONTEXT.request()