CODEWITHSUNDEEP
pythonuser-interfacetkinter
Jessica Chambers
Jessica Chambers

Reputation: 1326

Python/Tkinter : update class variable with a button

This is probably a silly question, but I couldn't find an answer to it on here, so here goes.

I'm setting up a Tkinter interface, and I'm only one button in. This button, when clicked should change the variable go to 1, I have done this by requiring it to call the function getGo(self) which is in the same class as the init function where the button was set up.

My problem is that it doesn't run the whole goTime() function: ie, it doesn't update my variable go.

init function:

class New_Toplevel_1:
    go=0
    def __init__(self, top=None):
        self.butGo = Button(top,command=lambda *args: goTime(self))
        self.butGo.place(relx=0.48, rely=0.84, height=41, width=65)
        self.butGo.configure(activebackground="#7bd93b")
        self.butGo.configure(font=font12)
        self.butGo.configure(text='''Go!''')

    def goTime(self):
        print("It's go time!")
        self.go=1
        print("go has been updated")

The output looks like this (repeated the number of times I clicked the button):

It's go time!
It's go time!
It's go time!
It's go time!

Why won't it update the variable? Or even show "go has been updated"? Thanks!

Upvotes: 0

Views: 460

Answers (1)

FJSevilla
FJSevilla

Reputation: 4543

You are passing the command argument incorrectly, just do:

self.butGo = Button(top, command=self.goTime)

To reference an instance method / attribute you must do self.method_name (self is just a convention)

If you need to pass arguments, you can use lambda:

command=lambda: self.go_time(5)
command=lambda n: self.go_time(n)
...

although I prefer functools.partial:

from functools import partial

class NewToplevel1:
    go = 0

    def __init__(self, top=None):
        self.butGo = Button(top, command=partial(self.go_time, 5))
        self.butGo.place(relx=0.48, rely=0.84, height=41, width=65)
        self.butGo.configure(activebackground="#7bd93b")

        self.butGo.configure(text='''Go!''')

    def go_time(self, n):
        print("It's go time!")
        self.go = n
        print("go has been updated")
        print(self.go)

Upvotes: 2

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