I am trying to use the invoke method of a ttk.Button, as shown at TkDocs (look at “The Command Callback”), but I keep getting this error:
AttributeError: ‘NoneType’ object has no attribute ‘invoke’
So, I tried this in the Interactive Shell:
ActivePython 220.127.116.11 (ActiveState Software Inc.) based on Python 3.1.1 (r311:74480, Aug 17 2009, 12:30:13) [MSC v.1500 32 bit (Intel)] on win32 from tkinter import * import tkinter.ttk as ttk root = Tk() button = ttk.Button(root, text="Test").grid(row=0, column=0) print(button) None
Which shows that ttk.Button returns None.
Is ttk.Button meant to return None. And, if so, why does TkDocs say that there is an invoke method?
No, you’re entirely wrong: your code does not show that
None — it shows that the
grid method on the button object returns
None! Don’t you see that you’re calling
.grid on whatever it is that
ttk.Button returns (the button object), and it’s the result of that grid call that you’re assigning to “button”?!
So do it right instead…:
button = ttk.Button(root, text="Test") button.grid(row=0, column=0)
now you can
print button and of course the results will be very different!-)