說明

1. 狀態(tài)機(jī)是一個非常實(shí)用的理論。在涉及到復(fù)雜的場景，建立狀態(tài)機(jī)模型，能帶來極大的方便。比如，網(wǎng)絡(luò)連接、模型狀態(tài)、業(yè)務(wù)邏輯。 2. 狀態(tài)機(jī)并不復(fù)雜, 重要的是它的思想，能夠極大減輕復(fù)雜度。使用時關(guān)鍵在于定義好事件和動作。

基本概念

State: 狀態(tài) Event: 事件. 事件觸發(fā)狀態(tài)變換 Action: 動作. event發(fā)生前或后執(zhí)行的動作 transition: 變換. 狀態(tài)變換

github

https://github.com/pytransitions/transitions

安裝

pip install transitions

簡單示例

# 連接協(xié)議狀態(tài)機(jī)from transitions.extensions import HierarchicalMachine as Machinefrom transitions.extensions.nesting import NestedState class ConnectionStateMachine: '''Connection state machine.''' def __init__(self, callbacks=None):''':param callbacks: callbacks for the state machine'''self.callbacks = {} # 定義狀態(tài)self.states = ['STATE_NOT_CONNECTED', { ’name’: 'STATE_CONNECTED', # 狀態(tài)名 ’on_enter’: self._on_enter_CONNECTED, # 進(jìn)入狀態(tài)觸發(fā) ’on_exit’: self._on_exit_CONNECTED, # 退出狀態(tài)觸發(fā) ’children’: [ # 狀態(tài)嵌套'STATE_NOT_SELECTED',{ ’name’: 'STATE_SELECTED', ’on_enter’: self._on_enter_CONNECTED_SELECTED} ] }] # transition 1self.machine = Machine(model=self, states=self.states, initial='STATE_NOT_CONNECTED', auto_transitions=False) if callbacks: self.callbacks = callbacks # 定義狀態(tài)變換self.machine.add_transition(’connect’, 'STATE_NOT_CONNECTED', 'STATE_CONNECTED_NOT_SELECTED') # transition 2self.machine.add_transition(’disconnect’, 'STATE_CONNECTED', 'STATE_NOT_CONNECTED') # transition 3self.machine.add_transition(’select’, 'STATE_CONNECTED_NOT_SELECTED', 'STATE_CONNECTED_SELECTED') # transition 4self.machine.add_transition(’deselect’, 'STATE_CONNECTED_SELECTED', 'STATE_CONNECTED_NOT_SELECTED') # transition 5self.machine.add_transition(’timeoutT7’, 'STATE_CONNECTED_NOT_SELECTED', 'STATE_NOT_CONNECTED') # transition 6 # 事件觸發(fā)的動作 def _on_enter_CONNECTED(self):if 'on_enter_CONNECTED' in self.callbacks: self.callbacks['on_enter_CONNECTED']() def _on_exit_CONNECTED(self):if 'on_exit_CONNECTED' in self.callbacks: self.callbacks['on_exit_CONNECTED']() def _on_enter_CONNECTED_SELECTED(self):if 'on_enter_CONNECTED_SELECTED' in self.callbacks: self.callbacks['on_enter_CONNECTED_SELECTED']()

定義狀態(tài)機(jī)

# 一般都是兩種：不嵌套、嵌套from transitions import Machine #不嵌套from transitions.extensions import HierarchicalMachine as Machine # 嵌套 # 檢查狀態(tài)machine.statemachine.is_<state_name>()

定義狀態(tài)

# 狀態(tài)可以是三種類型: 對象、字符串、字典from transitions import Statestates = [ State(name='solid'), # 對象 'liquid', # 字符串 {'name': 'gas'} # 字典]

定義變換

# 定義函數(shù)machine.add_transition(trigger, source, dest, )trigger(str) 方法名,觸發(fā)狀態(tài)轉(zhuǎn)換source(str or list) 源狀態(tài)dest(str) 目標(biāo)狀態(tài) # 加上變換machine.add_transition(trigger='wake_up', source='asleep', dest='hanging out')machine.add_transition(’work_out’, ’hanging out’, ’hungry’)machine.add_transition(’nap’, ’*’, ’asleep’) # 從任意狀態(tài)變?yōu)閍sleep

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