CODEWITHSUNDEEP
pythonuser-interfacetkinter
woff
woff

Reputation: 107

Python Tkinter button's callback not changing global variable

working on GUI Python at the moment. I've created a button that should change what a label says, however, I can't 'export' the new value of lbtext back into the global namespace. How do I do that? Here is my code:

from tkinter import *

lbtext = ""


def llb():
    global lbtext
    lbtext = "Hi"


master = Tk()

top = Canvas(master, name="gui")

but = Button(top, text="This is a button", command=llb)
but1 = Button(top, text='Meaning of life is: ', command=llb)
lb = Label(top, text=lbtext)

objs = [top, but, but1, lb]

for i in objs:
    i.pack()

mainloop()

Thanks!

Upvotes: 0

Views: 984

Answers (1)

Marcel Pfeiffer
Marcel Pfeiffer

Reputation: 1068

Accessing the global namespace works as you intended. The problem is the label updating.

This could only work if you are using a textvariable like:

v = StringVar()
lb = Label(top, textvariable=v)

In your case you have to actively update the label text in the llb callback:

lb.config(text=lbtext)

Upvotes: 2

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