在子类上使用Toplevel的Tkinter命令问题

Question

Trying to write a simple gui which has multiple child classes but the toplevel is not recognizing the attributes that I set with the command on a button so that it prints anything the user puts in the box. i have no clue why it isn't working on the child class

   from Tkinter import *
    import Tkinter as tk
    import tkSimpleDialog
    import tkMessageBox

    class MainWindow(tk.Frame):

        def __init__(self, *args, **kwargs):
            tk.Frame.__init__(self, *args, **kwargs)

            self.button = tk.Button(self, text="mx lookup",command=self.create_window)
            self.button.pack(side="left")





        def create_window(self):

            l = tk.Toplevel(self)
            l.entry = tk.Entry(l)
            l.button = tk.Button(l, text="search mx", command l.enter)

            l.entry.pack()
            l.button.pack()
        def enter(l):
            dns =(l.entry.get())
                  print(dns)






    if __name__ == "__main__":
        root = tk.Tk()
        main = MainWindow(root)
        main.pack(side="top", fill="both", expand=True)

        root.mainloop()

Answer 1

You're setting command l.enter it should be command = self.enter

To pass the widget (Toplevel) command = lambda: self.enter(l) or pass l.entry and then you can just call l.get()

Also I think you want dns = l.entry.get() to print the entry widgets text

You should add self at the beginning of your enter function as an argument to call self.enter with an additional arguement, or you could just refactor this outside of your class.

Answer 2

You have many issues with your code:

1. You have a typo in command l.enter . Correct it: command = self.enter
2. The notations l.entry and l.button are wrong because this means in Python that you have already created attributes called entry and button which you are now allowed to access with the dot notation as you did. You should rename these to something else. For example: l_entry and l_entry .
3. Consequently to 2. , in enter() you will need to modify l.entry.get() to l_entry.get()
4. To be able to use l_entry.get() in enter() method, you will need to write self.l_entry = tk.Button(self.l, text="search mx", command= self.enter) in create_window() and then in enter() write dns =(self.l_entry.get()) instead of dns =(l_entry.get()) .

Your program becomes now like this:

from Tkinter import *
import Tkinter as tk
import tkSimpleDialog
import tkMessageBox

class MainWindow(tk.Frame):
   def __init__(self, *args, **kwargs):
       tk.Frame.__init__(self, *args, **kwargs)
       self.button = tk.Button(self, text="mx lookup",command=self.create_window)
       self.button.pack(side="left")

   def create_window(self):
       self.l = tk.Toplevel(self)              
       self.l_entry = tk.Entry(self.l)
       self.l_button = tk.Button(self.l, text="search mx", command= self.enter)    
       self.l_entry.pack()
       self.l_button.pack()

   def enter(self):
       dns =(self.l_entry.get())
       print(dns)

if __name__ == "__main__":
   root = tk.Tk()
   main = MainWindow(root)
   main.pack(side="top", fill="both", expand=True)
   root.mainloop()