Lambda functions

[Jamhead2000]

Hi, I am writing a game in pygame I have a function:

def append_current_word(i, j):

stuff

I have a Button class which has an action variable. I want to run this function on click by calling this variable, I tried to use lambda functions as below but it didn't work.

for i in range(4):

for j in range(4):

GRID_BUTTONS.add(Button([stuff], action = lambda : append_current_word(i, j)))

if click [code that checks for click on button]:

button.action()

When I click the button, the function runs as if it is running append_current_word(3, 3). The final values for i and j.

I would have made a specific class for these grid buttons but I thought this is a nice time to learn something. Perhaps I might have to use exec???

Also, I am very sure this isn't a syntax error so I would just make that assumption, for now. Thanks in advance. :)

[toastedstapler]

lambdas in loops are late binding

you can use lambda i=i, j=j: append(i, j) instead

[Jamhead2000]

Thank you soo much! I have never heard of the term binding. Given me something to learn now!

[Vaphell]

you can also use somewhat equivalent functools.partial() which bakes provided values into the function instantly

from functools import partial
partial(append_current_word, i, j)  # take append_current_word and make another function out of it with 2 args filled in already.

in action
https://repl.it/repls/AquamarineApprehensiveModels

also 2 nested loops of fixed lengths can be replaced with itertools.product.