作为不相关的后续这个答案 https://stackoverflow.com/a/68269299/913098,它使用以下工作代码:
from transitions import Machine
from transitions import EventData
from typing import Callable
from enum import Enum, auto
class Observer:
def state_changed(self, event_data: EventData):
print(f"state is now '{event_data.state.name}'")
class State(Enum):
SOLID = auto()
LIQUID = auto()
GAS = auto()
class SubscribableMachine(Machine):
transitions = [
{'trigger': 'heat', 'source': State.SOLID, 'dest': State.LIQUID},
{'trigger': 'heat', 'source': State.LIQUID, 'dest': State.GAS},
{'trigger': 'cool', 'source': State.GAS, 'dest': State.LIQUID},
{'trigger': 'cool', 'source': State.LIQUID, 'dest': State.SOLID}
]
def __init__(self):
super().__init__(states=State, transitions=self.transitions,
initial=State.SOLID, send_event=True)
def subscribe(self, func: Callable, state: State):
self.get_state(state).on_enter.append(func)
def unsubscribe(self, func: Callable, state: State):
self.get_state(state).on_enter.remove(func)
machine = SubscribableMachine()
observer = Observer()
machine.subscribe(observer.state_changed, State.LIQUID)
machine.heat() # >>> state is now 'LIQUID'
machine.heat()
assert machine.state == State.GAS
machine.unsubscribe(observer.state_changed, State.LIQUID)
machine.cool() # no output
assert machine.state == State.LIQUID
我想要一个枚举Trigger
以及,就像我有一个State
.
唉,当我尝试时
class Trigger(Enum):
heat = auto()
cool = auto()
and
transitions = [
{'trigger': Trigger.heat, 'source': State.SOLID, 'dest': State.LIQUID},
{'trigger': Trigger.heat, 'source': State.LIQUID, 'dest': State.GAS},
{'trigger': Trigger.cool, 'source': State.GAS, 'dest': State.LIQUID},
{'trigger': Trigger.cool, 'source': State.LIQUID, 'dest': State.SOLID}
]
def __init__(self):
super().__init__(states=State, transitions=self.transitions,
initial=State.SOLID, send_event=True)
I get
Traceback (most recent call last):
File "C:/code/EPMD/Kodex/Algorithms/src/python/epmd/ablation_points/queries/dfgfdsg.py", line 42, in <module>
machine = SubscribableMachine()
File "C:/code/EPMD/Kodex/Algorithms/src/python/epmd/ablation_points/queries/dfgfdsg.py", line 33, in __init__
initial=State.SOLID, send_event=True)
File "C:\Code\EPMD\Kodex\EPD_Prerequisite\python_3.7.6\Lib\site-packages\transitions\core.py", line 589, in __init__
self.add_model(model)
File "C:\Code\EPMD\Kodex\EPD_Prerequisite\python_3.7.6\Lib\site-packages\transitions\core.py", line 607, in add_model
self._add_trigger_to_model(trigger, mod)
File "C:\Code\EPMD\Kodex\EPD_Prerequisite\python_3.7.6\Lib\site-packages\transitions\core.py", line 813, in _add_trigger_to_model
self._checked_assignment(model, trigger, partial(self.events[trigger].trigger, model))
File "C:\Code\EPMD\Kodex\EPD_Prerequisite\python_3.7.6\Lib\site-packages\transitions\core.py", line 807, in _checked_assignment
if hasattr(model, name):
TypeError: hasattr(): attribute name must be string
我可以通过使用来解决它Enum
's .name
:
transitions = [
{'trigger': Trigger.heat.name, 'source': State.SOLID, 'dest': State.LIQUID},
{'trigger': Trigger.heat.name, 'source': State.LIQUID, 'dest': State.GAS},
{'trigger': Trigger.cool.name, 'source': State.GAS, 'dest': State.LIQUID},
{'trigger': Trigger.cool.name, 'source': State.LIQUID, 'dest': State.SOLID}
]
但两者之间的不对称性State
and Trigger
打扰我。
难道我做错了什么?为什么枚举适用于State
但不是Trigger
?