Python 3 tkinter button command inside different class

Question

I'm creating a Python (3.4.3) - tkinter program and am wondering whether it is possible to reference a def (self.get_details) from inside another class for a button's command. I haven't been able to find an answer to this problem anywhere, so I figured I'd just ask.

Example:

import tkinter as tk
...

class Widgets(tk.Frame):
    def __init__(self, parent):
        tk.Frame.__init___(self, parent)
        self.parent = parent

        self.initUI()

    def initUI():

        # Lots of other different tkinter widgets go here

        self.button = tk.Button(command=App(get_details))
        self.button.pack()


class PopUp(tk.TopLevel): ....

class App(tk.Frame):
    def __init__(self, parent):
        tk.Frame.__init__(self, parent)
        self.parent = parent

        self.initUI()

    def get_details(self):

        # Complete a function

    def initUI(self):

        self.parent.title("My Application")
        self.style = Style()
        self.style.theme_use("default")

        self.pack()

        self.widgets = Widgets(self)
        self.widgets.pack(side="top", anchor="center", fill="both", expand=True)

if __name__ == "__main__":

    root = tk.Tk()
    App(root).pack(side="top", fill="both", expand=True)
    root.resizable(0,0)
    root.mainloop()

So I would like a button which belongs to the class Widgets() to call a command that is def get_details(self) which belongs to the class App(), which has the Widgets() class packed inside it.

I hope I was descriptive enough, it is fairly hard to word this problem. I am still kind of new to Python in general. Thanks!

Edit:

As suggested I changed it to self.parent.get_details(), which worked! However when I reference a tkinter widget from the Widgets() class inside def get_details() for example: self.button, I get:

AttributeError: 'App' object has no attribute 'button'

So I tried referencing the button as: self.parent.button, to which I received:

AttributeError: 'tkapp' object has no attribute 'button'

How should I be calling/referencing the button? Thanks!

Answer 1

In App, you create a Widgets object and save a reference to it named self.widgets. When you do so, you pass a reference to that App object into the Widgets object. That App instance reference is saved within the Widgets object as self.parent. Keep in mind that these two uses of self refer to different objects: while in App, self refers to the current instance of that App object. While in Widgets, self refers to the current instance of that Widgets object. To refer to something that's inside the other class, you have to use the proper reference and follow the path.

In an App instance:

self             this App instance
.widgets         the Widgets instance it contains
.button          the button in that Widget instance

In a Widgets instance:

self             this Widgets instance
.parent          the App object that created this Widgets object
.get_details     the get_details function in the parent App object

In the following, I've fixed your code's leftover bits (... causing syntax errors, Style not defined, etc.) and provided a small example of how to reference each object from the other one. The button initially says "hello", which you can change to "goodbye" by clicking it.

import tkinter as tk

class Widgets(tk.Frame):
    def __init__(self, parent):
        tk.Frame.__init__(self, parent)
        self.parent = parent

        self.initUI()

    def initUI(self):

        # Lots of other different tkinter widgets go here

        self.button = tk.Button(text='hello', command=self.parent.get_details)
        self.button.pack()

class App(tk.Frame):
    def __init__(self, parent):
        tk.Frame.__init__(self, parent)
        self.parent = parent

        self.initUI()

    def get_details(self):

        self.widgets.button.config(text='goodbye')

    def initUI(self):

        self.parent.title("My Application")

        self.pack()

        self.widgets = Widgets(self)
        self.widgets.pack(side="top", anchor="center", fill="both", expand=True)

if __name__ == "__main__":

    root = tk.Tk()
    App(root).pack(side="top", fill="both", expand=True)
    root.resizable(0,0)
    root.mainloop()