NameError: nom « clear_message » est pas défini

Question

from Tkinter import * 
import tkinter as tk # python3 

TITLE_FONT = ("Helvetica", 18, "bold") 


class SampleApp(tk.Tk): 

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

     # the container is where I stack a bunch of frames 
     # on top of each other, then the one we want visible 
     # will be raised above the others 
     container = tk.Frame(self) 
     container.pack(side="top", fill="both", expand=True) 
     container.grid_rowconfigure(0, weight=1) 
     container.grid_columnconfigure(0, weight=1) 

     self.frames = {} 
     for F in (MainPage,StorageOrMotor,Storage,Motor): 
      page_name = F.__name__ 
      frame = F(container, self) 
      self.frames[page_name] = frame 

      # put all of the pages in the same location; 
      # the one on the top of the stacking order 
      # will be the one that is visible. 
      frame.grid(row=0, column=0, sticky="nsew") 

     self.show_frame("MainPage") 

    def show_frame(self, page_name): 
     '''Show a frame for the given page name''' 
     frame = self.frames[page_name] 
     frame.tkraise() 


class MainPage(tk.Frame): 

    global user_key 
    global psw_key 
    user_key="" 
    psw_key="" 

#Here is the defined for clear_message `def` 
    def clear_message(): 
     user_key.delete(0, 'END') 
     psw_key.delete(0, 'END') 

    def __init__(self, parent, controller): 
     tk.Frame.__init__(self, parent) 
     self.controller = controller 
     Username = tk.Label(self, text="Username:",font=("Helvetica", "20","bold")) 
     Username.grid(row=2, column=3,columnspan=2) 
     Password = tk.Label(self, text="Password:",font=("Helvetica", "20","bold")) 
     Password.grid(row=3, column=3,columnspan=2) 

#............   
     Username_key = tk.Entry(self, textvariable = user_key, width=19, font=("Helvetica", "15")) 
     Username_key.grid(row=2, column=5,columnspan=5) 
     Password_key = tk.Entry(self, textvariable = psw_key, width=19, font=("Helvetica", "15")) 
     Password_key.grid(row=3, column=5,columnspan=5) 
     log_in = tk.Button(self, width=7, text="Log In", command=lambda: controller.show_frame("StorageOrMotor")) 
     log_in.grid(row=5,column=8,columnspan=2) 
#............`I try to create a clear button` 
     Clear = tk.Button(self, width=7, text=" Clear " ,command=lambda:clear_message()) 
     Clear.grid(row=5,column=5,columnspan=2) 

Answer 1

clear_message() appartient à la classe MainPage donc lorsque vous appelez à l'intérieur de cette classe, vous devez utiliser le préfixe self.. En outre, vous devez utiliser self en tant que paramètre lors de la définition de la méthode car il est membre d'une classe.

def clear_message(self): #self here 
    user_key.delete(0, 'END') 
    psw_key.delete(0, 'END') 

De plus, étant donné que clear_message ne prend aucun argument, vous n'avez pas besoin d'une expression lambda là.

#self here and removed lambda 
Clear = tk.Button(self, width=7, text=" Clear " ,command=self.clear_message)