Question

Basically, I want to have a button which, when pressed, will add stuff to my window. Here’s some minimum code:

from Tkinter import *

def create_line (N):
    """ """
    Label (root, text= "Color ").grid(row=N, column=0, padx=3)
    OptionMenu (root, v, *optionList).grid(row=N, column=1, padx=3)
    Button (root, text="+", command=add_line(N)).grid(row=N, column=2, padx=3)

def add_line (M):
    M = M +1
    Label (root, text= "Color ").grid(row=M, column=0, padx=3)
    OptionMenu (root, v, *optionList).grid(row=M, column=1, padx=3).grid(row=M,     
                 column=2, padx=3)
    return 1

root = Tk()
optionList = ("red", "green", "blue")
current_row = 0
v = StringVar()
v.set(optionList[0])
create_line(current_row)
mainloop()

If you comment out the code inside the add_line function (except the return line) and run the code, you will see a label, an options menu, and a button. I want the ‘+’ button to create another row with the same widgets. This minimum code is not my real app, but this is the core of what I can’t do.

I know it can be done, because I have an app I downloaded that changes the menu options dynamically when I button is pressed, but that technique doesn’t seem to work for me.

Thanks.

Answer 1

One problem that I see right away is:

Button (root, text="+", command=add_line(N)).grid(row=N, column=2, padx=3)

should be:

Button (root, text="+", command=lambda:add_line(N)).grid(row=N, column=2, padx=3)

As it is written, you’re calling the function add_line when the Button is created, not when it is pressed.