"TypeError: 'NoneType' object does not support item assignment" 如何解决此问题？

Question

我目前正在尝试用python制作一个计算器，我首先为它创建了一个简单的GUI。然而，在使按钮工作的同时，我在尝试输出数字时不断出现类型错误。如何解决此问题？在编写所需的所有其他命令之前，我已经开始尝试输出0进行测试运行。

import tkinter as t
window = None
display_label = None
expression = ''

def setup_GUI():

global window
global dsiplay_label
window = t.Tk()
window.title("calculator")

display_label = t.Label(window, textvariable='', anchor='e', relief=t.GROOVE, width=15, font='Arial 20')
display_label.grid(row=0, column=0, columnspan=4, padx=10, pady=10)

#numbers
btn1 = t.Button(window, text='1', width=5, height=2, font='Arial 15',command = press0)
btn2 = t.Button(window, text='2', width=5, height=2, font='Arial 15')
btn3 = t.Button(window, text='3', width=5, height=2, font='Arial 15')
btn4 = t.Button(window, text='4', width=5, height=2, font='Arial 15')
btn5 = t.Button(window, text='5', width=5, height=2, font='Arial 15')
btn6 = t.Button(window, text='6', width=5, height=2, font='Arial 15')
btn7 = t.Button(window, text='7', width=5, height=2, font='Arial 15')
btn8 = t.Button(window, text='8', width=5, height=2, font='Arial 15')
btn9 = t.Button(window, text='9', width=5, height=2, font='Arial 15')
btn0 = t.Button(window, text='0', width=5, height=2, font='Arial 15')
#operators
clear = t.Button(window, text = "C", width=5, height=2, font='Arial 15')
percent = t.Button(window, text = "％", width=5, height=2, font='Arial 15')
squared = t.Button(window, text = "X²", width=5, height=2, font='Arial 15')
ineq = t.Button(window, text = "＜", width=5, height=2, font='Arial 15')
period = t.Button(window, text = "ㆍ", width=5, height=2, font='Arial 15')
mul = t.Button(window, text = "×", width=5, height=2, font='Arial 15')
div = t.Button(window, text = "÷", width=5, height=2, font='Arial 15')
add = t.Button(window, text = "+", width=5, height=2, font='Arial 15')
sub = t.Button(window, text = "-", width=5, height=2, font='Arial 15')
result = t.Button(window, text = "=", width=5, height=2, font='Arial 15')

#positions
btn1.grid(row=2, column=0)
btn2.grid(row=2, column=1)
btn3.grid(row=2, column=2)
btn4.grid(row=3, column=0)
btn5.grid(row=3, column=1)
btn6.grid(row=3, column=2)
btn7.grid(row=4, column=0)
btn8.grid(row=4, column=1)
btn9.grid(row=4, column=2)
btn0.grid(row=5, column=1)
clear.grid(row=1, column=0)
result.grid(row=5, column=2)
add.grid(row=2, column=3)
sub.grid(row=3, column=3)
mul.grid(row=4, column=3)
div.grid(row=5, column=3)
period.grid(row=5, column=0)
ineq.grid(row=1, column=1)
percent.grid(row=1,column=2)
squared.grid(row=1,column=3)


def press0():
global expression
expression = expression + '0'
display_label['text']= expression

setup_GUI()
window.mainloop()

Answer 1

当在GUI函数中定义全局变量display_label时，您将其拼写错误。

Answer 2

您将display_label拼错为global dsiplay_label。