Question

此代码是泳池记分牌的开始。直到我按下按钮，它才会起作用，然后出现一个回溯，说“分配之前已被引用”。这是完整的代码，尽管您可能不需要全部：

from tkinter import*
import tkinter.messagebox as box

window = Tk()
window.configure(bg = 'white')
frame_stripes = Frame(window, bg = 'white')
frame_spots = Frame(window, bg = 'white')

stripes = 7
spots = 7
stripe_fouls = 0
spot_fouls = 0

def another_go():
    box.showinfo('Another Go', 'You get another go')
def foul_2_gos():
    box.showinfo('Extra Go', 'Your opponent gets 2 goes')

def stripes_pot():
    stripes -= 1
    another_go()
stripes_plus = Button(frame_stripes, text = 'Stripes Pot', command = stripes_pot)

def stripes_foul_add():
    stripes_fouls += 1
    foul_2_goes()
stripes_foul = Button(frame_stripes, text = 'Stripes Foul', command = stripes_foul_add)

def spots_pot():
    spots -= 1
    another_go()
spots_plus = Button(frame_spots, text = 'Spots Pot', command = spots_pot)

def spots_foul_add():
    spots_fouls += 1
    foul_2_goes()
spots_foul = Button(frame_spots, text = 'Spots Foul', command = spots_foul_add)

stripes_plus.pack()
spots_plus.pack()
stripes_foul.pack()
spots_foul.pack()

frame_stripes.pack(padx = 30, pady = 30)
frame_spots.pack(padx = 30, pady = 30)

window.mainloop()

回溯如下：

Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Users\Dylan.DESKTOP-7RLU752\AppData\Local\Programs\Python\Python37\lib\tkinter\__init__.py", line 1702, in __call__
    return self.func(*args)
  File "C:\Users\Dylan.DESKTOP-7RLU752\Desktop\Pool Score Counter.py", line 26, in stripes_foul_add
    stripes_fouls += 1
UnboundLocalError: local variable 'stripes_fouls' referenced before assignment

Answer 1

您已经在函数之前声明了stripes，然后在函数内部对其进行了引用，但是在每个函数内部，您必须通过添加{{1}来声明要使用全局变量stripes。 }。您应该对导致异常的每个变量执行此操作。

global stripes

Answer 2

由于未指定变量应全局使用而收到错误。您可以通过如下修改功能来实现：

def stripes_pot():
    global stripes
    stripes -= 1
    another_go()
stripes_plus = Button(frame_stripes, text = 'Stripes Pot', command = stripes_pot)

def stripes_foul_add():
    global stripes_fouls
    stripes_fouls += 1
    foul_2_goes()
stripes_foul = Button(frame_stripes, text = 'Stripes Foul', command = stripes_foul_add)

def spots_pot():
    global spots
    spots -= 1
    another_go()
spots_plus = Button(frame_spots, text = 'Spots Pot', command = spots_pot)

def spots_foul_add():
    global spots_fouls
    spots_fouls += 1
    foul_2_goes()
spots_foul = Button(frame_spots, text = 'Spots Foul', command = spots_foul_add)

也就是说，使用全局变量并不总是一个好主意。对于您的项目，基于类的实现会更好。

为什么会出现“分配前被引用”错误？

2 个答案: