Problem dynamically creating tkinter elements

Question

I really don't understand this.. The text of y is fine but when it is passed into the lambda function to print y it just prints 2.

It seems simple yet I don't get it.

Could someone explain or tell me how I can fix this?

Thanks

from tkinter import *

window = Tk()

buttonHeight = 10
buttonWidth = 25

gridItemsList = [['-', '-', '-'], ['-', '-', '-'],['-', '-', '-']]
for y in range (0, 3):
    for x in range(0, 3):           
            gridItemsList[2-y][x] = ([Button(window, height=buttonHeight, width=buttonWidth, background="white", text=y, command=lambda:print(y)), [] ])
            gridItemsList[2-y][x][0].grid(column = y, row=x, padx=20, pady=20)

mainloop()

it doesn't copy value from y when you create button. All buttons keep only reference to variable y and get value from y when you press button - and when you press button then y has last value from for-loop. Using command=lambda a=y:print(a) it copies value from y when you create button so every button has different value. — furas
– furas, Commented Sep 29, 2019 at 20:05

Samuel Kazeem · Accepted Answer · 2019-09-29 20:13:48Z

1

 y in range(0,3)

gives

 y=0, y=1, y=2

Hence when your widgets are being created the value of y is changing via the loop(0,1,2), hence the button text are OK. but at the end of the loop, the value of y is y=2.

Hence, you will always get 2 as the output of your print functions because the buttons are only available to use after the loop is done and the last value and current value of y is 2 after the loop.

answered Sep 29, 2019 at 20:13

Samuel Kazeem

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