While循环不会实时更新

Question

I wrote this code using python for raspberry pi. But I am struggling with the code. The while loop doesn't break.

w=1
z=0

def auto_1(w,z):
    w=1
    z=0
    return w,z

def manual_1(w,z):
    w=0
    z=1
    return w,z

GPIO.add_event_detect(Manual, GPIO.RISING, callback=lambda *i: manual_1(w,z), bouncetime=300)
GPIO.add_event_detect(Auto, GPIO.RISING, callback=lambda *i: auto_1(w,z), bouncetime=300)

while w==1:
      print("Auto")
      pfr_mains_1(PFRMains,PFRGen,GenStartOut,MainsCont,GenCont)
      pfr_mains_0(PFRMains,PFRGen,GenStartOut,MainsCont,GenCont)
      time.sleep(3)
      if w==0:
         break

The while loop doesn't break even though the "manual" event detected. The code runs fine but the loop does not break when an event detected. It seems the w value does not get updated from the initial value. But I have no clue what to do. Please help me with this.Thank you.

Answer 1

Your main script body is using the global variable w. However, the two functions you defined have each their own local variable w. Anything these functions do to w stays inside the respective function.

You could declare w as global in both functions to always access the global w, but that's not really good practice. It would be better to assign the functions' result to the global w.