标签未在python tkinter中更新

Question

I'm writing a tkinter program, and I'm trying to update my label on the ui. However I can't get it to work. Here's the code:

from tkinter import *
import random, functools, string

root = Tk()

word_list = ["APPLE", "PEAR", "BANNANA"]

word = word_list [random.randint(0,2)]

hidden_word = ["_ "] * len(word)
print (word)


abc = ['_ '] * len(word)
guessed_letters = []

#Functions
def click_1 (key):
    if key in word:
        guessed_letters = ''.join([key])
        global abc
        abc = ''.join([key if key in guessed_letters else "_" for key in word])
    else:
        print ("Nope") ####TESTING#####


#Frames
hangman_frame = Frame(root)
hangman_frame.grid(row=0, column=0, sticky=N)
letter_frame = Frame(root)
letter_frame.grid(row=1, column=0, sticky=S)

#Label
letters_label = Label(hangman_frame, textvariable=abc)
letters_label.grid(row=0, column=0, sticky=W)

(Just an excerpt, not all)

My question is that when ran, this section appears not to work:

letters_label = Label(hangman_frame, textvariable=abc)

where:

abc = ['_ '] * len(word)
    guessed_letters = []

#Functions
def click_1 (key):
    if key in word:
        guessed_letters = ''.join([key])
        global abc
        abc = ''.join([key if key in guessed_letters else "_" for key in word])

And nothing shows up, whereas when this is put:

letters_label = Label(hangman_frame, text=abc)

The label shows up, but does not update when the function click_1 is called.

Any reason to this? Thanks in advance.

Answer 1

The reason is that the textvariable option requires an instance of StringVar or IntVar . You can't just pass it the name of a normal variable.

Generally speaking, you never need to use the textvariable option unless you specifically need the features of a StringVar or IntVar (such as having two widgets share the same data, or doing traces on the variable). I know lots of examples use it, but it just adds another object that you don't really need.

In order to update the text on a label, you would do this:

letters_label = Label(..., text="initial value")
...
def click_1(...):
    ...
    abc = ...
    letters_label.configure(text=abc)