Python 变量覆盖自身

Question

我有以下代码块。 fanSensor() 会自动运行，但如果我调用 fanOn()，fanOverride 会将其自身设置回 0。有人可以帮我弄清楚我要做什么吗？做错了吗？

..顺便说一句，休眠 while 循环线程会节省处理能力吗？..

import RPi.GPIO as GPIO
import os
import time
import _thread

fanOnTemp = 57
fanOffTemp = 54
fanPin = 40
currentTemp = 0.0
fanOverride = 0

GPIO.setmode(GPIO.BOARD) #Labels the pins by order on the board
GPIO.setup(fanPin, GPIO.OUT) #Allows control of fanPin

def getFanState():
    print(GPIO.input(fanPin)) #Prints the state of the fanPin

def fanOn():
    GPIO.output(fanPin, 1)  #Set fanPin on
    fanOverride = 1

def fanOff():
    GPIO.output(fanPin, 0) #Set fanPin off
    fanOverride = 0

def getTempF():
    print(Temp()*(9/5)+32)

def getTemp():
    print(Temp())

def Temp():
    seconds=10
    x=0
    for i in range(0,seconds):
        temp=((os.popen('vcgencmd measure_temp').readline()).replace("temp=","").replace("'C\n",""))
        x+=float(temp)
        time.sleep(1) #Sleep the thread for 1 second
    x=x/seconds #Calculate the average temperature
    return(x)

def fanSensor():
    while 1:
        time.sleep(5)
        currentTemp = float((os.popen('vcgencmd measure_temp').readline()).replace("temp=","").replace("'C\n",""))
        print ("Fan Temperature: %.2f" % currentTemp) #removes all but 2 decimal places
        print ("Fanoverride: "+str(fanOverride))
        if fanOverride == 0: #Check for fan override on
            if currentTemp > fanOnTemp:
                GPIO.output(fanPin, 1)
            elif currentTemp < fanOffTemp:
                GPIO.output(fanPin, 0)

_thread.start_new(fanSensor,())

Answer 1

假设算法正确，如果您需要两个函数共享其状态(即作用于同一个变量)，则需要将 fanOverride 声明为全局

def fanOn():
    global fanOverride
    GPIO.output(fanPin, 1)  #Set fanPin on
    fanOverride = 1

def fanOff():
    global fanOverride
    GPIO.output(fanPin, 0) #Set fanPin off
    fanOverride = 0

看看this SO Q&A有关全局的更多信息