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from automat import MethodicalMachine
class Lock(object):
"A sample I/O device."
def engage(self):
print("Locked.")
def disengage(self):
print("Unlocked.")
class Turnstile(object):
machine = MethodicalMachine()
def __init__(self, lock):
self.lock = lock
@machine.input()
def arm_turned(self):
"The arm was turned."
@machine.input()
def fare_paid(self):
"The fare was paid."
@machine.output()
def _engage_lock(self):
self.lock.engage()
@machine.output()
def _disengage_lock(self):
self.lock.disengage()
@machine.output()
def _nope(self):
print("**Clunk!** The turnstile doesn't move.")
@machine.state(initial=True)
def _locked(self):
"The turnstile is locked."
@machine.state()
def _unlocked(self):
"The turnstile is unlocked."
_locked.upon(fare_paid, enter=_unlocked, outputs=[_disengage_lock])
_unlocked.upon(arm_turned, enter=_locked, outputs=[_engage_lock])
_locked.upon(arm_turned, enter=_locked, outputs=[_nope])
turner = Turnstile(Lock())
print("Paying fare 1.")
turner.fare_paid()
print("Walking through.")
turner.arm_turned()
print("Jumping.")
turner.arm_turned()
print("Paying fare 2.")
turner.fare_paid()
print("Walking through 2.")
turner.arm_turned()
print("Done.")
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