automat_tea_kettle_state_machine_with_transitions.py

1from automat import MethodicalMachine
2
3class TeaKettle(object):
4    _machine = MethodicalMachine()
5
6    @_machine.input()
7    def heat_water(self):
8        "Heat the water."
9
10    @_machine.output()
11    def _begin_heating(self):
12        print("Heating...")
13
14    @_machine.state(initial=True)
15    def cold(self):
16        "The water is cold."
17
18    @_machine.state()
19    def heating(self):
20        "The water is heating."
21
22    @_machine.state()
23    def boiling(self):
24        "The water is boiling."
25
26    @_machine.input()
27    def wait_for_boil(self):
28        "Wait for the water to boil."
29
30    @_machine.output()
31    def _is_boiling(self):
32        print("It's boiling!")
33
34    cold.upon(
35        heat_water,
36        enter=heating,
37        outputs=[_begin_heating]
38    )
39
40    heating.upon(
41        wait_for_boil,
42        enter=boiling,
43        outputs=[_is_boiling]
44    )
45
46# Usage example:
47kettle = TeaKettle()
48kettle.heat_water()
49kettle.wait_for_boil()