使用 class 方法创建 TKinter label

Question

I am trying use object oriented programming style to write the code for a Tkinter app. I want to use a class method to place labels(or other widgets) to the GUI. The code I wrote is adding a character which I don't expect to the GUI. How can I write the initial add_label method so that it does not add the unwanted character. Below is my code and a screenshot. I am new to OOP, so i might be missing something.

from tkinter import *
class App:
    def __init__(self, parent):
        self.widgets(root)
        self.add_label(root)

    def widgets(self, app):
        self.title = Label(app, text= 'LABEL UP').pack()
        self.btn = Button(app, text = 'BUTTON').pack()
    def add_label(self, text):
        Label(text= text).pack()

root = Tk()
App(root)
App.add_label(root, 'LABEL_1')
App.add_label(root,'LABEL_2')
root.mainloop()

I am new to OOP and stil trying to figure out how i can benefit from code reuse in this case. My app has several widgets and functions

Answer 1

What do you expect self.add_label(root) to do? According to your method definition, it takes text as argument, so when you say self.add_label(root) , you are passing root as text . And what is root ? It is '.' , so remove it and it'll be gone.

Though a proper way to do this will be to pass a parent argument to the method and use that while widget creation:

And the important part is, your instantiating the class wrong. Keep a reference to it, rather than creating a lot of instances.

from tkinter import *

class App:
    def __init__(self, parent):
        self.widgets(root)

    def widgets(self, app):
        self.title = Label(app, text= 'LABEL UP').pack()
        self.btn = Button(app, text = 'BUTTON').pack()
    
    def add_label(self, parent, text):
        Label(parent,text= text).pack()

root = Tk()

app = App(root)
app.add_label(root, 'LABEL_1')
app.add_label(root,'LABEL_2')

root.mainloop()

Try not to get confused with both the mistakes.

How would I write this class? I don't know the true purpose of this, but I think you can follow something like this:

from tkinter import *

class App:
    def __init__(self, parent):
        self.parent = parent
        
        self.title = Label(self.parent, text='LABEL UP')
        self.title.pack()

        self.entry = Entry(self.parent)
        self.entry.pack()

        self.btn = Button(self.parent, text='BUTTON')
        # Compliance with PEP8
        self.btn.config(command=lambda: self.add_label(self.entry.get())) 
        self.btn.pack()

    def add_label(self, text):
        Label(self.parent, text=text).pack()

    def start(self):
        self.parent.mainloop()

root = Tk()

app = App(root)
app.start()