面向对象的Tkinter编码：改变文本和更新

Question

所以我一直在自学自己面向对象编程的Tkinter项目，因为我清楚地看到它们对于大量编码更加有组织。然而，我必须承认，我一直在通过简单地复制来自在线的各种编码，而不是完全理解它的目的是什么。

这让我觉得我的代码根本不起作用，我不知道为什么不行。第一个问题是简单地改变其他小部件的一个问题。

我有这样的示例代码：

import Tkinter as tk 

LARGE_FONT = ("Verdana", 12) 

class SeaofBTCapp(tk.Tk): 
    def __init__(self, *args, **kwargs): 
     tk.Tk.__init__(self, *args, **kwargs) 
     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 = {} 
     frame = StartPage(container, self) 
     self.frames[StartPage] = frame 

     frame.grid(row = 0, column = 0, sticky = "nsew") 

     self.show_frame(StartPage) 

    def show_frame(self, cont): 
     frame = self.frames[cont] 
     frame.tkraise() 

class StartPage(tk.Frame): 
    def __init__(self, parent, controller): 
     tk.Frame.__init__(self, parent) 
     label = tk.Label(self, text = "Start Page", font = LARGE_FONT) 
     label.pack(pady = 10, padx = 10) 
     button = tk.Button(self, text = "Change Label", command = self.change) 
     button.pack(pady = 10, padx = 10) 

    def change(self): 
     label["text"] = "It has changed" 

app = SeaofBTCapp() 
app.mainloop() 

这应该是一个很简单的代码，按下一个按钮，标签从“起始页”改为“它改变了”。但是每当我运行它时，它都会说全局变量“label”没有被定义。此外，如果我然后将其更改为self.label，则表明StartPage实例没有属性“标签”。我不知道我做错了什么。

此外，以类似的方式，我正在研究一个SideBar类和一个Main类绑定到一个MainApplication类的项目。 Main类获取一个值并将其显示在Main类的Frame中。在此之后，SideBar中的按钮将该值增加1.但Main显示屏不会更新，我不知道如何将Side更新与SideBar中的按钮绑定。

import Tkinter as tk 

something = [0, 6] 

class Main(): 
    def __init__(self, root): 
     mainboard = tk.Frame(root, height = 100, width = 100) 
     self.maincanvas = tk.Canvas(mainboard, bd = 1, bg = "white") 

     mainboard.grid(row = 0, column = 0) 
     self.maincanvas.grid(row = 0, column = 0) 

     self.maincanvas.create_text(45, 50, anchor = "center", text = str(something[1])) 

class SideBar(): 
    def __init__(self, root): 
     sidebarframe = tk.Frame(root, height = 100, width = 100) 
     button = tk.Button(sidebarframe, width = 20, text = "Change Value", command = self.add) 

     sidebarframe.grid(row = 0, column = 1) 
     button.grid(row = 0, column = 0) 

    def add(self): 
     something[1] += 1 
     print something[1] 


class MainApplication(): 
    def __init__(self, parent): 
     self.parent = parent 
     self.sidebar = SideBar(self.parent) 
     self.main = Main(self.parent) 

if __name__ == "__main__": 
    root = tk.Tk() 
    MainApplication(root) 
    root.mainloop() 

所有帮助将不胜感激，但请尽量不要用大量的专业术语，因为我仍然在学习。

Answer 1

在第一个场景替换：

label = tk.Label(self, text = "Start Page", font = LARGE_FONT) 
label.pack(pady = 10, padx = 10) 

有了：

self.label = tk.Label(self, text = "Start Page", font = LARGE_FONT) 
self.label.pack(pady = 10, padx = 10) 

以及在功能change把它像这样：

self.label["text"] = "It has changed" 

而且在你的第二个问题，我改变了一下代码，所以它的工作原理：

import Tkinter as tk 

something = [0, 6] 

class Main(): 
    def __init__(self, root): 
     mainboard = tk.Frame(root, height = 100, width = 100) 
     self.maincanvas = tk.Canvas(mainboard, bd = 1, bg = "white") 

     mainboard.grid(row = 0, column = 0) 
     self.maincanvas.grid(row = 0, column = 0) 

     self.maincanvas.create_text(45, 50, anchor = "center", text = str(something[1])) 

class SideBar(): 
    def __init__(self, root, main): 
     self.main = main            # Putting the main object to self.main 
     sidebarframe = tk.Frame(root, height = 100, width = 100) 
     button = tk.Button(sidebarframe, width = 20, text = "Change Value", command = self.add) 

     sidebarframe.grid(row = 0, column = 1) 
     button.grid(row = 0, column = 0) 

    def add(self): 
     something[1] += 1 
     self.main.maincanvas.delete("all")               # Removing everything from canvas 
     self.main.maincanvas.create_text(45, 50, anchor = "center", text = str(something[1]))  # Inserting the new value 
     print something[1] 


class MainApplication(): 
    def __init__(self, parent): 
     self.parent = parent 
     self.main = Main(self.parent)      # The main needs to run first 
     self.sidebar = SideBar(self.parent, self.main)  # So that SideBar can use its canvas 

if __name__ == "__main__": 
    root = tk.Tk() 
    MainApplication(root) 
    root.mainloop()