如何中断while循环、运行函数并返回到循环

Question

我从Python和Raspberry Pi开始，并尝试用它们进行一些物理计算。

我从这个开始：https://www.raspberrypi.org/learning/physical-computing-with-python/，一切都很顺利。

然后我试着玩红绿灯(成功了！)：https://www.raspberrypi.org/learning/physical-computing-with-python/trafficlights/

下面是我的代码：

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()

然后我试着在人行横道上加一个按钮。但在这里我遇到了问题。

代码如下：

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()

我尝试了button.wait_for_press，button.wait_for_release & Co.，但button.is_pressed给了我最好的结果。

问题是，当我按下按钮时，函数被调用，但循环仍在继续。那么我如何重写代码，然后当我按下按钮时，循环停止，函数被调用，函数中的所有事情都完成了，然后它又回到了循环中？

或者有另一种解决方案，使用其他按钮属性？

提前感谢！

Answer 1

如下所示，不是在按下按钮时直接调用行人过街函数，而是设置一个变量来指示行人过街按下触发器，然后在while循环内部调用pedestrian_crossing函数，如果按下则返回while循环

将对pedestrian_press变量的检查放在my_sleep函数中，这样每次在while循环中调用my_sleep时，它都会得到检查，这使得它几乎延迟了~1s

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()