Build dumb little "state machines" with Python decorators.
To install decorstate from pip:
$ pip install decorstateTo install decorstate from source:
$ git clone git@github.com:ahawker/decorstate.git
$ cd decorstate
$ python setup.py installHow do I use this pile?
import decorstate
class Switch(object):
state = 'off'
@decorstate.transition('off', 'on')
def on(self, *args, **kwargs):
print 'You turned me on!'
@decorstate.transition('on', 'off')
def off(self, *args, **kwargs):
print 'You turned me off!'
>>> switch = Switch()
>>> switch.state
'off'
>>> switch.on()
You turned me on!
'on'
>>> switch.off()
You turned me off!
'off'A switch? Really? How lame.
import decorstate
class BrokenSwitch(object):
state = 'off'
@decorstate.transition('off', 'on')
def on(self, *args, **kwargs):
print 'You turned me on!'
@decorstate.transition('on', 'off')
def off(self, *args, **kwargs):
print 'You turned me off? Nah!'
@off.guard
def off(self, *args, **kwargs):
print 'Ha! I laugh at your feeble attempt!'
>>> broken_switch = BrokenSwitch()
>>> broken_switch.state
'off'
>>> broken_switch.on()
You turned me on!
'on'
>>> broken_switch.off()
Ha! I laugh at your feeble attempt!
'on'
>>> broken_switch.state
'on'
>>> broken_switch.off()
Ha! I laugh at your feeble attempt!
'on'
>>> broken_switch.state
'on'A broken switch? Yawn.
import decorstate
class InstantOffSwitch(object):
state = 'off'
@decorstate.transition('off', 'off')
def on(self, *args, **kwargs):
print 'You turned me on!'
@decorstate.transition('on', 'off')
def off(self, *args, **kwargs):
print 'You turned me off!'
@on.after
def on(self, *args, **kwargs):
print 'Ha! No light for you!'
>>> instant_off_switch = InstantOffSwitch()
>>> instant_off_switch.state
'off'
>>> instant_off_switch.on()
You turned me on!
Ha! No light for you!
'off'
>>> instant_off_switch.state
'off'Well, that's kinda mean.
import decorstate
import random
class IoTSwitch(object):
state = 'off'
@decorstate.transition('off', 'off')
def on(self, *args, **kwargs):
print 'You turned me on? Maybe...'
@decorstate.transition('on', 'off')
def off(self, *args, **kwargs):
print 'You turned me off? Maybe...'
@on.guard
def on(self, *args, **kwargs):
return self.coin_flip()
@off.guard
def off(self, *args, **kwargs):
return not self.coin_flip()
@staticmethod
def coin_flip():
return random.randint(1, 2) == 1
>>> iot_switch = IoTSwitch()
>>> iot_switch.state
'off'
>>> iot_switch.on()
'off'
>>> iot_switch.on()
'off'
>>> iot_switch.on()
'off'
>>> iot_switch.on()
You turned me on? Maybe...
'on'
>>> iot_switch.off()
'on'
>>> iot_switch.off()
'on'
>>> iot_switch.off()
'on'
>>> iot_switch.off()
'on'
>>> iot_switch.off()
You turned me off? Maybe...
'off'Hey now, why you hating? Internet powered light switches are next level shit. My living room has its own twitter feed.
I was interesting in doing something a bit more complex using the Python descriptor protocol.
Random thoughts and musing about potential changes/features.
- Consider adding the @machine decorator back as currently, you cannot use the "state", "transition" and "transition_event" attributes until the first transition has been performed since they are lazy created.
- Add event handler that fires only when "entering" a state and not when you perform multiple transitions but stay in the same state.