Question

I create a new Button object but did not specify the command option upon creation. Is there a way in Tkinter to change the command (onclick) function after the object has been created?

Answer 1

Though Eli Courtwright’s program will work fine¹, what you really seem to want though is just a way to reconfigure after instantiation any attribute which you could have set when you instantiated². How you do so is by way of the configure() method.

from Tkinter import Tk, Button  def goodbye_world():     print 'Goodbye World!\nWait, I changed my mind!'     button.configure(text = 'Hello World!', command=hello_world)  def hello_world():     print 'Hello World!\nWait, I changed my mind!'     button.configure(text = 'Goodbye World!', command=goodbye_world)  root = Tk() button = Button(root, text='Hello World!', command=hello_world) button.pack()  root.mainloop() 

¹ ‘fine’ if you use only the mouse; if you care about tabbing and using [Space] or [Enter] on buttons, then you will have to implement (duplicating existing code) keypress events too. Setting the command option through .configure is much easier.

² the only attribute that can’t change after instantiation is name.