Tkinter pass a button as argument-CodePudding

I'm new to Tkinter and as my first project I wanted to create a Tic Tac Toe. I want to create 9 buttons, that will change their background image when I click on them, the problem is that I dont want to create a function for every single button but one function that will take the button in argument and will change its background image.

The code I wrote:


def play(bid):
    if player == "X":
        bid.config(image=cross)
    if player == "O":
        bid.config(image=circle)

b1 = tk.Button(app, text="", image=white, command=lambda id=b1: play(id))
b1.grid(column=0, row=0)

How can I pass b1 as an argument to play() function? Thanks

I tried to use b1 as an argument to play(), and use play() to change b1's image. When I try to run this code I get "name b1 is not defined".

CodePudding user response：

Define a single function to create, configure, and bind your button; then your callback can close over the necessary variable referring to your button. Something like

def play(bid):
    if player == "X":
        bid.config(image=cross)
    if player == "O":
        bid.config(image=circle)

def add_button(app, r, c):
    b = tk.Button(app, text="", image=white)
    b.config(command=lambda: play(b))
    b.grid(column=c, row=r)
    return b

for row in [0,1,2]:
    for col in [0,1,2]:
        # Save the return value somewhere if necessary
        addButton(app, row, col)

The lambda expression contains a free variable b, which refers to the variable b in the closest enclosing scope, which is the call to add_button where the lambda expression is evaluated.

CodePudding user response：

One way you can do it is to separate the creation of the button from the assignment using the .config method.

b1 = tk.Button(app, text="", image=white)
b1.config(command=lambda btn_id=b1: play(btn_id))

This is not really the best way to go about it, it's better to instead pass something that defines the button like an Enum or text.

b1 = tk.Button(app, text="", image=white, command=lambda : play("b1"))

then check that "b1" is the input in your function, this way b1 can be redefined as what would happen in loops.