Python设计模式(十三)【状态模式】

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"""状态模式的实现"""
from __future__ import print_function

class State(object):
"""基本状态。这是共享的功能"""
def scan(self):
"""扫描拨盘到下一状态"""
self.pos += 1
if self.pos == len(self.stations):
self.pos = 0
print("扫描... 状态是", self.stations[self.pos], self.name)

class AmState(State):

def __init__(self, radio):
self.radio = radio
self.stations = ["1250", "1380", "1510"]
self.pos = 0
self.name = "AM"

def toggle_amfm(self):
print("切换到FM...")
self.radio.state = self.radio.fmstate

class FmState(State):

def __init__(self, radio):
self.radio = radio
self.stations = ["81.3", "89.1", "103.9"]
self.pos = 0
self.name = "FM"

def toggle_amfm(self):
print("切换到AM...")
self.radio.state = self.radio.amstate

class Radio(object):

"""一台收音机。它有一个扫描按钮，和一个AM / FM切换开关。"""

def __init__(self):
"""我们有一个AM状态和FM状态"""
"""AmState继承了State"""
self.amstate = AmState(self)
self.fmstate = FmState(self)
"""初始化am状态"""
self.state = self.amstate

def toggle_amfm(self):
self.state.toggle_amfm()

def scan(self):
self.state.scan()

# 测试入口
if __name__ == '__main__':
radio = Radio()
actions = [radio.scan] * 2 + [radio.toggle_amfm] + [radio.scan] * 2
actions *= 2

for action in actions:
action()

运行结果如图: