How to have parameters to a button command in tkinter python3 [duplicate]

Question

I want to have UI where when I press a button, stuff pops up in the console. The issue is the stuff prints into the console before I press the button. After some testing, I have found that if I don't use parenthesis to call my function in the command argument, it works fine.

ex: A function called hello prints hello world in the console, so I would call it like button=Button(master, command=hello) instead of button=Button(master, command=hello())

The issue with this way is I can't use parameters.

here is an example of a code similar to mine:

index={'Food':['apple', 'orange'], 'Drink':['juice', 'water', 'soda']}
Names=['Food', 'Drink']

def display(list):
    for item in list:
        print(item)

from tkinter import *
mon=Tk()
app=Frame(mon)
app.grid()

for item in Names:
    button=Button(mon, text=item, command=diplay(index[item]))
    button.grid()
mon.mainloop()

Any ideas of how to be able to use parameters? I hope this all made sense, but if it didn't please leave a comment. Thank You.

Did you try pasting your question's title into a Google search? — TigerhawkT3
– TigerhawkT3, Commented Jun 18, 2015 at 19:12

maccartm · Accepted Answer · 2015-06-18 19:25:21Z

3

You are looking for the lambda keyword:

from tkinter import *
index={'Food':['apple', 'orange'], 'Drink':['juice', 'water', 'soda']}
Names=['Food', 'Drink']

def display(list):
    for item in list:
        print(item)

mon=Tk()
app=Frame(mon)
app.grid()

for item in Names:
    Button(mon, text=item, command= lambda name = item: display(index[name])).grid()
mon.mainloop()

You have to use name = item so that every time a button is initialized, it takes the current value of item from the for loop.

If for example you used lambda: display(index[item]), both buttons would display the values for 'Drink' because that is the last value of the lambda function initialized in the loop.

answered Jun 18, 2015 at 19:25

maccartm

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1 Comment

Pythogen Over a year ago

Thankyou, instead of marking it as duplicate like the rest

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