Why don't Button clicks do anything?

Question

from tkinter import *

def plus():
    print('Hello')

root = Tk()

Btn = Button(root, text="Show", command=plus()).pack()

root.mainloop()

Note also that `Btn` is not storing what you think it is. If you want to store a reference to `Btn` don't pack it in the same instruction line as the `Button` constructor call. Just make `Btn.pack()` in the next line. — progmatico, Jan 11 '18 at 21:46
Possible duplicate of [Tkinter buttons help](https://stackoverflow.com/questions/4046118/tkinter-buttons-help) — Aran-Fey, Jan 11 '18 at 21:47

score 3 · Accepted Answer · answered Jan 11 '18 at 21:40

3

No need for lambda. Just remove the () in Btn = Button(root, text="Show", command=plus()).pack(). This is causing you to call the function before actually pressing the button.

Your button command should look like this:

Btn = Button(root, text="Show", command=plus).pack()

answered Jan 11 '18 at 21:40

Xantium

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how to get text from entry. entry.get() doesn't work – lukyjuranek Jan 11 '18 at 21:52
@user8921550 Can I see some code or something. I can't guess. – Xantium Jan 11 '18 at 21:54
1

@user8921550 - edit your answer please, and add the code you posted as comment before. – progmatico Jan 11 '18 at 21:56
impor.... root=Tk def click(): print(E.get()) E = Entry(root) E.pack() btn = Button(root, text="click", command=click) btn.pack() – lukyjuranek Jan 11 '18 at 23:33
@user8921550 `from tkinter import * root = Tk() def click(): print(E.get()) E = Entry(root) E.pack() btn = Button(root, text="click", command=click) btn.pack() ` Works perfectly for me. You just missed the () on Tk. – Xantium Jan 11 '18 at 23:38
@user8921550 Please check your code again. This is working fine for me. – Xantium Jan 12 '18 at 12:32
I am sorry, it works. I don't know where was the mistake. – lukyjuranek Jan 12 '18 at 12:55
I am sorry. The code is correct – lukyjuranek Jan 12 '18 at 12:58
@user8921550 I think `root=Tk` was the problem. That should be `root=Tk()` – Xantium Jan 12 '18 at 13:25
@user8921550. you may also [want to accept](https://stackoverflow.com/help/someone-answers) but only do that if you are satisfied with it and it did actually help. – Xantium Jan 12 '18 at 20:46

JimmyCarlos · Answer 2 · 2018-01-11T21:46:36.687

2

You could use a lambda. Code:

from tkinter import *
def plus(): print('Hello')
root = Tk()
Btn = Button(root, text="Show", command=lambda:plus()).pack()
root.mainloop()

Per the requests of the Anti-Lambda league below me, here is a non-lambda version:

from tkinter import *
def plus(): print('Hello')
root = Tk()
Btn = Button(root, text="Show", command=plus).pack()
root.mainloop()

edited Jan 11 '18 at 21:46

answered Jan 11 '18 at 21:38

JimmyCarlos

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It doesn't have to be a lambda, not in this case, and not in many other cases. Usually you need a lambda to pass parameters into the callback. – progmatico Jan 11 '18 at 21:44
Why use lambda? This is unnecessary (not wrong). Just remove the `()` – Xantium Jan 11 '18 at 21:44
You're right, the lambda wasn't necessary. Alternate version added. – JimmyCarlos Jan 11 '18 at 21:47

Why don't Button clicks do anything?

2 Answers2