State Machines in Python

This is a simple implementation for state machines in Python. State machines define their logic in terms of states and transitions. Transitions are triggered by signals or the expiration or timers.

Installation

pip install stmpy

Example: Tick Tock State Machine

from stmpy import Machine, Driver

class Tick:

  def __init__(self):
    self.ticks = 0
    self.tocks = 0

  def on_init(self):
    print('Init!')
    self.stm.start_timer('tick', 1000)

  def on_tick(self):
    print('Tick!')
    self.ticks = self.ticks + 1
    self.stm.start_timer('tock', 1000)

  def on_tock(self):
    print('Tock!')
    self.tocks = self.tocks + 1
    self.stm.start_timer('tick', 1000)


driver = Driver()
tick = Tick()

t0 = {'source':'initial', 'target':'s_tick', 'effect':'on_init'}
t1 = {'trigger':'tick', 'source':'s_tick', 'target':'s_tock', 'effect':'on_tick'}
t2 = {'trigger':'tock', 'source':'s_tock', 'target':'s_tick', 'effect':'on_tock'}

stm_tick = Machine(transitions=[t0, t1, t2], obj=tick, name='stm_tick')
tick.stm = stm_tick

driver.add_stm(stm_tick)
scheduler.start(max_transitions=5)
scheduler.wait_until_finished()