python-2.7 - 运行时 Tkinter 按钮 'not defined'

Question

我正在按照在线快速指南开始在 Python (2.7) 中使用 Tk，到目前为止，我有以下代码:

from Tkinter import *

root = Tk()
root.title("Note Taker")

root.mainloop()

button1 = Button(root, text="button1", command = Button1)
button2 = Button(root, text="button2", command = Button2)
button3 = Button(root, text="button3", command = Button3)


text = Entry(root)
listbox = Listbox(root)


text.pack()
button1.pack()
button2.pack()
button3.pack()
listbox.pack()


def Button1():
    listbox.insert(END, "button1 pressed")

def Button2():
    listbox.insert(END, "button2 pressed")

def Button3():
    text_contents = text.get()
    listbox.insert(END, text_contents)
    text.delete(0,END)

但是，当我运行此命令时，GUI 已加载，但没有显示任何按钮，而是给出了此“NameError”:

button1 = Button(root, text="button1", command = Button1)
NameError: name 'Button1' is not defined

我确定这纯粹是我的错误，但是可以更改什么才能使其正确运行？

Answer 1

移动

def Button1():
    listbox.insert(END, "button1 pressed")

之前

button1 = Button(root, text="button1", command=Button1)

因为 command = Button1 引用 Button1。

当然，对 Button2 和 Button3 执行相同的操作。

---

同时移动

root.mainloop()

到脚本的底部，因此在定义 Tkinter 小部件之前，控制流不会陷入事件循环中。

---

from Tkinter import *

root = Tk()
root.title("Note Taker")


def Button1():
    listbox.insert(END, "button1 pressed")


def Button2():
    listbox.insert(END, "button2 pressed")


def Button3():
    text_contents = text.get()
    listbox.insert(END, text_contents)
    text.delete(0, END)


button1 = Button(root, text="button1", command=Button1)
button2 = Button(root, text="button2", command=Button2)
button3 = Button(root, text="button3", command=Button3)

text = Entry(root)
listbox = Listbox(root)

text.pack()
button1.pack()
button2.pack()
button3.pack()
listbox.pack()

root.mainloop()