Tkinter Function attached to Button executed immediately [duplicate] - python

This question already has answers here:
How can I pass arguments to Tkinter button's callback command?
(2 answers)
Closed 6 years ago.
What I need is to attach a function to a button that is called with a parameter. When I write the code as below however, the code is executed once when the button is created and then no more. Also, the code works fine if I get rid of the parameter and parentheses when I declare the function as an attribute of the button. How can I call the function with a parameter only when the button is pressed?
from Tkinter import *
root =Tk()
def function(parameter):
print parameter
button = Button(root, text="Button", function=function('Test'))
button.pack()
root.mainloop()

The solution is to pass the function as a lambda:
from Tkinter import *
root =Tk()
def callback(parameter):
print parameter
button = Button(root, text="Button", command=lambda: callback(1))
button.pack()
root.mainloop()
Also, as #nbro already correctly pointed out, the button attribute is command, not function.

Related

Tkinter buttons calling functions without pressing them [duplicate]

This question already has answers here:
Why is my Button's command executed immediately when I create the Button, and not when I click it? [duplicate]
(5 answers)
Closed last year.
I've had this problem for a while. When I start a program, any tkinter buttons will call their functions without being pressed or anything. and after that, I cannot use the button anymore because it only works once for some reason. Can anybody help?
This is not the actual code, but it is an example:
from tkinter import *
root = Tk()
def function():
print("activated")
button = Button(root, text="this is a button", command=function)
button.pack()
root.mainloop()
Apparently adding parentheses at the end of the command inside the button code was the problem. credit to #jasonharper for this one.

Call a function after pressing a button (tkinter) [duplicate]

This question already has answers here:
Why is my Button's command executed immediately when I create the Button, and not when I click it? [duplicate]
(5 answers)
Closed 2 years ago.
I created a button "button" and I want to call a function "function" when I press on this button.
When I run the program, the function is called and then the button appears. If I press it once again, the function is not called. So how to disable calling the function without pressing the button and how to enable calling the function at each press on the butotn?
from tkinter import *
def function():
what this function does
root = Tk()
button = Button(root,text="Call function", command=function())
button.pack()
root.mainloop()
You need to pass the function (don't call it):
button = Button(root,text="Call function", command=function)
I think you have to remove the brackets from the function, because you just want to give the function as a parameter to your button and you do not want to call the function instead.
So it will look like:
button = Button(root,text="Call function", command=function)

Problem regarding messagebox module in Tkinter [duplicate]

This question already has answers here:
Why is my Button's command executed immediately when I create the Button, and not when I click it? [duplicate]
(5 answers)
Closed 2 years ago.
My message box launches automatically without me clicking the button first when I run it in Pycharm.
from tkinter import *
from PIL import ImageTk,Image
from tkinter import messagebox
root = Tk()
root.title('Frame')
root.iconbitmap('D:\Tkinter\Frame.ico')
def popup():
messagebox.showinfo("Popup","You have clicked a button!")
Button(root, text = 'Click Me!',commmand=popup()).pack()
root.mainloop()
And this is what I get when I run it
In Button declaration, you are calling your function instead of passing a callback to it.
There is also a typo in a word 'command' - you wrote it with 3x m.
So, you should declare your button as:
Button(root, text = 'Click Me!',command=popup).pack()
How to create a basic button

Button in tkinter is calling a function before being pressed [duplicate]

This question already has answers here:
Why is my Button's command executed immediately when I create the Button, and not when I click it? [duplicate]
(5 answers)
Closed 6 years ago.
I am programming with tkinter in python 2.7. Used this syntax dozens of times but for some reason in this specific occurrence after I declare the button it calls the function without me pressing it..
here is the code:
def uninstall_win():
verify = Tk()
verify.title("Uninstall")
recheck = make_entry(verify, "Please Re-enter password:", 14, show='*')
b = Button(verify, borderwidth=4, text="Uninstall", pady=8, command=uninstall(recheck.get()))
b.pack()
verify.mainloop()
def make_entry(parent, caption, width=None, **options):
Label(parent, text=caption).pack(side=TOP)
entry = Entry(parent, **options)
if width:
entry.config(width=width)
entry.pack(side=TOP, padx=10, fill=BOTH)
return entry
any insight will be appreciated
You should use lambda when putting a function with arguments in a Button.
b = Button(verify, borderwidth=4, text="Uninstall", pady=8, command=lambda: uninstall(recheck.get()))
Becuase you're calling the function instead of passing the function as a callable.
lambda: uninstall(recheck.get())
Passing uninstall(recheck.get()) is setting the command to be what this function returns

How do I get a button to display a label when clicked using tkinter? [duplicate]

This question already has answers here:
Why is my Button's command executed immediately when I create the Button, and not when I click it? [duplicate]
(5 answers)
Closed 7 years ago.
I want to make a button that displays a label when clicked. Here was my thinking:
from Tkinter import *
def write_hello():
w = Label(root, text = "Hello. This is a label.")
w.pack()
root = Tk()
button = Button(root, text = "Hello!", command = write_hello() )
button.pack()
root.mainloop()
Can anyone be nice enough to walk me through this? I'm very new.
You're calling the write_hello function before you even create the button, so what you're probably seeing is the label showing up before the button on the UI (and without clicking it). What you want to do is pass the function to the Button constructor instead of the function's return value:
button = Button(root, text = "Hello!", command = write_hello)

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