Python State Machine - States

states.py

class State(object):
    """
    We define a state object which provides some utility functions for the
    individual states within the state machine.
    """

    def __init__(self):
        print 'Processing current state:', str(self)

    def on_event(self, event):
        """
        Handle events that are delegated to this State.
        """
        pass

    def __repr__(self):
        """
        Leverages the __str__ method to describe the State.
        """
        return self.__str__()

    def __str__(self):
        """
        Returns the name of the State.
        """
        return self.__class__.__name__


# Start of our states
class LockedState(State):
    """
    The state which indicates that there are limited device capabilities.
    """

    def on_event(self, event):
        if event == 'pin_entered':
            return UnlockedState()

        return self


class UnlockedState(State):
    """
    The state which indicates that there are no limitations on device
    capabilities.
    """

    def on_event(self, event):
        if event == 'device_locked':
            return LockedState()

        return self
# End of our states.