Passing arguments into a callback function-CodePudding

I'm currently writing a Python program using Tkinter. In it, I want to trace the text within several entry boxes. Is there anyway I can pass parameters into the callback function that I call within the trace method? For example:

def cb(*args, var):
        do something 

some_object.trace("w", cb(var=some_var))

when I try this, I get a None Type error, which I'm assuming is because of how I'm attempting to pass in the argument.

CodePudding user response：

You're calling the function immediately, and passing its return value as the callback argument, not passing the function as a callback.

Use lambda to create a function that calls the function with an extra argument.

some_object.trace("w", lambda *args: cb(*args, var=some_var))

You can also use functools.partial to create a function with some arguments pre-specified.

from functools import partial

some_object.trace("w", partial(cb, var=some_var))