automat_methodical_machine_state_transitions_coffee_kettle.py

1from __future__ import print_function
2from automat import MethodicalMachine
3
4class CoffeeMachine(object):
5    _machine = MethodicalMachine()
6
7    @_machine.input()
8    def brew_button_pressed(self):
9        "The user pressed the 'brew' button."
10
11    @_machine.output()
12    def _begin_heating(self):
13        print("Heating up the water...")
14
15    @_machine.state(initial=True)
16    def idle(self):
17        "The machine is waiting for someone to press the button."
18
19    @_machine.state()
20    def brewing(self):
21        "The machine is brewing coffee."
22
23    @_machine.output()
24    def _finish_brewing(self):
25        print("Coffee is ready!")
26
27    @_machine.input()
28    def heating_finished(self):
29        "The internal heater has finished heating the water."
30
31    # Define the transitions
32    idle.upon(
33        brew_button_pressed,
34        enter=brewing,
35        outputs=[_begin_heating]
36    )
37
38    brewing.upon(
39        heating_finished,
40        enter=idle,
41        outputs=[_finish_brewing]
42    )
43
44# Example usage:
45coffee_machine = CoffeeMachine()
46coffee_machine.brew_button_pressed()
47coffee_machine.heating_finished()