python - Tcl 错误 : can't invoke "destroy" command: application has been destroyed

Question

我是一名 Python 初学者。尝试制作一个新按钮来关闭窗口。我收到错误消息:

Exception in Tkinter callback Traceback (most recent call last): File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk/Tkinter.py", line 1536, in call return self.func(*args) File "tk_cp_successful.py", line 138, in buttonPushed self.root.destroy() File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk/Tkinter.py", line 1859, in destroy self.tk.call('destroy', self._w) TclError: can't invoke "destroy" command: application has been destroyed

class LoginPage(tk.Frame):
   def __init__(self, parent, controller):
      self.controller = controller
      self.root = tk.Tk()
      global entry_1
      global entry_2
      tk.Frame.__init__(self, parent)
      label = tk.Label(self, text="Welcome to VISA Login Page",fg="blue")
      label.pack(pady=10,padx=10)

      label_1 = Label(self, text="Username")
      label_1.pack()
      label_2 = Label(self, text="Password")
      label_2.pack()
      entry_1 = Entry(self)
      entry_1.pack()
      entry_2 = Entry(self, show="*")
      entry_2.pack()
      label_1.grid(row=0, sticky=E)
      label_1.pack()
      label_2.grid(row=1, sticky=E)
      label_2.pack()
      entry_1.grid(row=0, column=1)
      entry_1.pack()
      entry_2.grid(row=1, column=1)
      entry_2.pack()
      checkbox = Checkbutton(self, text="Keep me logged in")

      checkbox.grid(columnspan=2)
      checkbox.pack()
      logbtn = Button(self, text="Login", command = self._login_btn_clickked)
      logbtn.grid(columnspan=2)
      logbtn.pack()
      myButton = Button(self, text="Exit",command = self.buttonPushed)
      myButton.pack()

  def buttonPushed(self):
      self.root.destroy()

  def _login_btn_clickked(self):
      #print("Clicked")
      username = entry_1.get()
      password = entry_2.get()

      #print(username, password)

      if username == "test" and password == "test":
          #box.showinfo("Login info", "Welcome Tester")
          button1 = ttk.Button(self, text="Please click, Welcome to login!!!",
                     command=lambda: self.controller.show_frame(StartPage))
          button1.pack()
      else:
          box.showerror("Login failed", "Incorrect username")

Answer 1

你的代码有很多问题

1. 缩进错误
2. 混合 grid() 和 pack()
3. 你是import tkinter as tk还是from tkinter import *，即
   self.root = tk.Tk()(导入为 tk)或
   label_1 = Label(self, text="Username")(from tkinter import *)
4. 程序中没有mainloop
5. 在一个类中使用全局是没有必要的，而且风格很差

无论如何，以下修改后的代码都会运行，希望它能有所帮助。

import sys
if sys.version_info[0] < 3:
    import Tkinter as tk     ## Python 2.x
else:
    import tkinter as tk     ## Python 3.x

class LoginPage():
   def __init__(self):
      self.root=tk.Tk()
      label = tk.Label(self.root, text="Welcome to VISA Login Page",fg="blue")
      label.grid(row=0)

      label_1 = tk.Label(self.root, text="Username")
      label_2 = tk.Label(self.root, text="Password")
      self.entry_1 = tk.Entry(self.root)
      self.entry_2 = tk.Entry(self.root, show="*")
      label_1.grid(row=1, sticky="e")
      label_2.grid(row=2, sticky="e")
      self.entry_1.grid(row=1, column=1)
      self.entry_2.grid(row=2, column=1)

      ## doesn't do anything at this time
      ##checkbox = tk.Checkbutton(self.root, text="Keep me logged in")
      ##checkbox.grid(row=3, columnspan=2)

      logbtn = tk.Button(self.root, text="Login", command = self._login_btn_clickked)
      logbtn.grid(row=9, columnspan=2)
      myButton = tk.Button(self.root, text="Exit",command = self.buttonPushed)
      myButton.grid(row=10)

      self.root.mainloop()

   def buttonPushed(self):
      self.root.destroy()

   def _login_btn_clickked(self):
      #print("Clicked")
      username = self.entry_1.get()
      password = self.entry_2.get()

      #print(username, password)

      if username == "test" and password == "test":
          print "OK login"
          #box.showinfo("Login info", "Welcome Tester")
          #button1 = ttk.Button(self.root, text="Please click, Welcome to login!!!",
          #           command=lambda: self.controller.show_frame(StartPage))
          #button1.pack()
      else:
          #box.showerror("Login failed", "Incorrect username")
          print "Error"

LP=LoginPage()