150 lines
2.9 KiB
Python
150 lines
2.9 KiB
Python
#!/usr/bin/env python
|
|
# -*- encoding: utf-8 -*-
|
|
"""
|
|
Topic: 实现状态对象或状态机
|
|
Desc :
|
|
"""
|
|
|
|
|
|
class Connection:
|
|
"""普通方案，好多个判断语句，效率低下~~"""
|
|
|
|
def __init__(self):
|
|
self.state = 'CLOSED'
|
|
|
|
def read(self):
|
|
if self.state != 'OPEN':
|
|
raise RuntimeError('Not open')
|
|
print('reading')
|
|
|
|
def write(self, data):
|
|
if self.state != 'OPEN':
|
|
raise RuntimeError('Not open')
|
|
print('writing')
|
|
|
|
def open(self):
|
|
if self.state == 'OPEN':
|
|
raise RuntimeError('Already open')
|
|
self.state = 'OPEN'
|
|
|
|
def close(self):
|
|
if self.state == 'CLOSED':
|
|
raise RuntimeError('Already closed')
|
|
self.state = 'CLOSED'
|
|
|
|
|
|
class Connection1:
|
|
"""新方案——对每个状态定义一个类"""
|
|
|
|
def __init__(self):
|
|
self.new_state(ClosedConnectionState)
|
|
|
|
def new_state(self, newstate):
|
|
self._state = newstate
|
|
# Delegate to the state class
|
|
|
|
def read(self):
|
|
return self._state.read(self)
|
|
|
|
def write(self, data):
|
|
return self._state.write(self, data)
|
|
|
|
def open(self):
|
|
return self._state.open(self)
|
|
|
|
def close(self):
|
|
return self._state.close(self)
|
|
|
|
|
|
# Connection state base class
|
|
class ConnectionState:
|
|
@staticmethod
|
|
def read(conn):
|
|
raise NotImplementedError()
|
|
|
|
@staticmethod
|
|
def write(conn, data):
|
|
raise NotImplementedError()
|
|
|
|
@staticmethod
|
|
def open(conn):
|
|
raise NotImplementedError()
|
|
|
|
@staticmethod
|
|
def close(conn):
|
|
raise NotImplementedError()
|
|
|
|
|
|
# Implementation of different states
|
|
class ClosedConnectionState(ConnectionState):
|
|
@staticmethod
|
|
def read(conn):
|
|
raise RuntimeError('Not open')
|
|
|
|
@staticmethod
|
|
def write(conn, data):
|
|
raise RuntimeError('Not open')
|
|
|
|
@staticmethod
|
|
def open(conn):
|
|
conn.new_state(OpenConnectionState)
|
|
|
|
@staticmethod
|
|
def close(conn):
|
|
raise RuntimeError('Already closed')
|
|
|
|
|
|
class OpenConnectionState(ConnectionState):
|
|
@staticmethod
|
|
def read(conn):
|
|
print('reading')
|
|
|
|
@staticmethod
|
|
def write(conn, data):
|
|
print('writing')
|
|
|
|
@staticmethod
|
|
def open(conn):
|
|
raise RuntimeError('Already open')
|
|
|
|
@staticmethod
|
|
def close(conn):
|
|
conn.new_state(ClosedConnectionState)
|
|
|
|
|
|
c = Connection1()
|
|
print(c._state)
|
|
c.open()
|
|
|
|
# Alternative implementation
|
|
class State:
|
|
def __init__(self):
|
|
self.new_state(State_A)
|
|
|
|
def new_state(self, state):
|
|
self.__class__ = state
|
|
|
|
def action(self, x):
|
|
raise NotImplementedError()
|
|
|
|
|
|
class State_A(State):
|
|
def action(self, x):
|
|
# Action for A
|
|
pass
|
|
self.new_state(State_B)
|
|
|
|
|
|
class State_B(State):
|
|
def action(self, x):
|
|
# Action for B
|
|
pass
|
|
self.new_state(State_C)
|
|
|
|
|
|
class State_C(State):
|
|
def action(self, x):
|
|
# Action for C
|
|
pass
|
|
self.new_state(State_A)
|