[Python] Closing a Tkinter toplevel

I'm trying to understand what happens when you close a toplevel window, specifically, at what point it becomes unreferenced and eligible for garbage collection.

I have put together the code below and this works as I would expect. You open the toplevel with the button, close the toplevel with the cross in the corner and the destructor executes its code.

from tkinter import *
from tkinter import ttk


class TestClass(Toplevel):
def __init__(self, *args, **kwargs):
Toplevel.__init__(self, *args, **kwargs)

self.title('A New Window')

print ('window created')

def __del__(self):
print('destructor called')


def AButtonPress():
#create a device window
new_window = TestClass(root)
root.wait_window(new_window)
print("window closed")


root = Tk()

a_button=ttk.Button(root,text="Press Me",command=AButtonPress)
a_button.grid(column=0, row=0)


root.mainloop()


However, when I add any widgets to the toplevel, say for example a label, when you close the toplevel, the destructor is no longer called.

from tkinter import *
from tkinter import ttk


class TestClass(Toplevel):
def __init__(self, *args, **kwargs):
Toplevel.__init__(self, *args, **kwargs)

self.title('A New Window')

print ('window created')

#create a widget
self.a_label=ttk.Label(self,width=15,text = "A Label")
self.a_label.grid(column=0, row=0)


def __del__(self):
print('destructor called')


def AButtonPress():
#create a toplevel object
new_window = TestClass(root)
root.wait_window(new_window)
print("window closed")


root = Tk()

a_button=ttk.Button(root,text="Press Me",command=AButtonPress)
a_button.grid(column=0, row=0)


root.mainloop()


Does this now mean that the toplevel will no longer get garbage collected and repeated opening and closing of the toplevel will consume memory?

Am I looking too much into this?

Continue reading...