如何中斷while循環，運行函數並返回循環

Question

我已經開始使用Python和Raspberry Pi，並試圖使用它們進行一些物理計算。

我從那開始：https://www.raspberrypi.org/learning/physical-computing-with-python/，一切都很順利。

比我試圖玩弄紅綠燈（成功！）： https://www.raspberrypi.org/learning/physical-computing-with-python/trafficlights/

這裏我的代碼：

from gpiozero import Button, TrafficLights 
from time import sleep 

lights = TrafficLights(25, 8, 7) 

while True: 
    lights.green.on() 
    print("GREEN") 
    sleep(12) 
    lights.green.off() 
    lights.amber.on() 
    print("AMBER") 
    sleep(4) 
    lights.red.on() 
    lights.amber.off() 
    print("RED") 
    sleep(12) 
    lights.amber.on() 
    print("RED & AMBER") 
    sleep(4) 
    lights.red.off() 
    lights.amber.off() 

比我嘗試添加一個按鈕，一個人行橫道。但在這裏我有問題。

下面的代碼：

from gpiozero import Button, TrafficLights 
from time import sleep 

button = Button(21) 
lights = TrafficLights(25, 8, 7) 

def pedestrian_crossing(): 
    sleep(4) 
    lights.off() 
    lights.amber.on() 
    print("Pedestrian crossing: AMBER") 
    sleep(4) 
    lights.red.on() 
    lights.amber.off() 
    print("Pedestrian crossing: RED") 
    sleep(12) 
    lights.amber.on() 
    print("Pedestrian crossing: RED & AMBER") 
    sleep(4) 
    lights.red.off() 
    lights.amber.off() 

button.when_pressed = pedestrian_crossing 

while True: 
    lights.green.on() 
    print("GREEN") 
    sleep(12) 
    lights.green.off() 
    lights.amber.on() 
    print("AMBER") 
    sleep(4) 
    lights.red.on() 
    lights.amber.off() 
    print("RED") 
    sleep(12) 
    lights.amber.on() 
    print("RED & AMBER") 
    sleep(4) 
    lights.red.off() 
    lights.amber.off() 

我試圖與button.wait_for_press，button.wait_for_release &有限，但button.is_pressed是給我的最好成績之一。

問題是，當我按下按鈕時，函數被調用，但循環繼續。那麼我怎樣才能重寫代碼，而不是當我按下循環停止的按鈕時，函數被調用，函數內的所有內容都已完成，然後又回到循環？

還有另一種解決方案，與其他按鈕屬性？

在此先感謝！

Answer 1

如何像下面，而是調用的人行橫道功能時，直接按下按鈕，設置一個變量來表示人行橫道扣動扳機，那裏面while循環將調用pedestrian_crossing功能，如果是按然後返回到while循環

把檢查的pedestrian_press VAR在my_sleep功能，因此它會得到檢查每次my_sleep是在while循環中調用，使得它幾乎〜1秒延時中斷

pedestrian_press = False 
def pedestrian_crossing(): 
    global pedestrian_press 
    pedestrian_press = False # reset press 
    sleep(4) 
    lights.off() 
    lights.amber.on() 
    print("Pedestrian crossing: AMBER") 
    sleep(4) 
    lights.red.on() 
    lights.amber.off() 
    print("Pedestrian crossing: RED") 
    sleep(12) 
    lights.amber.on() 
    print("Pedestrian crossing: RED & AMBER") 
    sleep(4) 
    lights.red.off() 
    lights.amber.off() 

def set_pedestrian_press(): 
    global pedestrian_press 
    pedestrian_press = True 

button.when_pressed = set_pedestrian_press 


def my_sleep(n): 
    # checking for pedestrian press done at 1 sec interval 
    # to make it check at smaller interval 
    # change to range(n*10) then sleep(0.1), for 0.1s interval 
    for i in range(n): 
     sleep(1) 
     if pedestrian_press: # check if pedestrian press 
      pedestrian_crossing() 

while True: 
    lights.green.on() 
    print("GREEN") 
    my_sleep(12) # every second will check for pedestrian_press 
    lights.green.off() 
    lights.amber.on() 
    print("AMBER") 
    my_sleep(4) # every second will check for pedestrian_press 
    lights.red.on() 
    lights.amber.off() 
    print("RED") 
    my_sleep(12) # every second will check for pedestrian_press 
    lights.amber.on() 
    print("RED & AMBER") 
    my_sleep(4) # every second will check for pedestrian_press 
    lights.red.off() 
    lights.amber.off()