Python Tkinter，用循环设置按钮回调函数 [英] Python Tkinter, setting up button callback functions with a loop

问题描述

我正在编写一个显示按钮网格的程序，当按下按钮时，我希望它打印出网格中按钮的位置(行列")到控制台.这是我所拥有的

I'm writing a program that displays a grid of buttons, when a button is pressed I want it to print the location of the button in the grid ("row column") out to the console. Here is what I have

import Tkinter as tk

class board(tk.Tk):
    def __init__(self, parent=None):
        tk.Tk.__init__(self,parent)
        self.rows = 5
        self.columns = 5
        self.init_board()

    def init_board(self):
        for i in range(self.rows):
            for j in range(self.columns):
                cmd = lambda: self.button_callback(i,j)
                b = tk.Button(self, text=str("  "), command=cmd)
                b.grid(row=i, column=j)

    def button_callback(self, row, col):
        print(str(row) + " " + str(col))


if __name__ == '__main__':
    board().mainloop()

问题是，当我单击任何按钮时，我会打印出4 4"，这是循环中实例化的最后一个按钮的位置.我不知道为什么会发生这种情况，请帮助！

the problem is that when I click on any of the buttons I get "4 4" printed out which is the location of the last button instantiated in the loop. I don't know why this is happening, please help!

推荐答案

在使用lambda创建的函数中，i，j指的是init_board 函数中的变量，在 for 循环结束后设置为 4、4.

In the function created using lambda, i, j refers to the varaible in the init_board function, which are set to 4, 4 after the for loop ends.

您可以使用默认参数解决此问题.

You can workaround this using default argument.

替换以下行:

cmd = lambda: self.button_callback(i,j)

与:

cmd = lambda i=i, j=j: self.button_callback(i,j)

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