Tkinter Radiobutton 在已选择的情况下执行命令

Question

在我的 Tkinter 应用程序中，我想在使用

on_choice

选择

Radiobutton

时执行

command=on_choice

函数。当按下已选择的单选按钮时，不应再次执行该功能。它只能在从另一个单选按钮切换后执行一次，因此用户不能通过按下同一个单选按钮来重复执行功能。有没有办法在已选择

Radiobutton

时阻止执行命令？

代码：

import tkinter as tk

def on_choice():
    print('Function executed')

root = tk.Tk()
root.geometry('300x150')

radiobutton_variable = tk.StringVar()
radiobutton_variable.set(1)
button_1 = tk.Radiobutton(root, text='Button 1', variable=radiobutton_variable, value=1, command=on_choice)
button_2 = tk.Radiobutton(root, text='Button 2', variable=radiobutton_variable, value=2, command=on_choice)

button_1.pack()
button_2.pack()

root.mainloop()

Answer 1

一个简单的解决方案是使用一个变量来跟踪最后按下的是哪个

Radiobutton

（我在这里称之为

prev_btn

）。

command

函数可以检查该值，并且仅当该值自上次调用该函数以来发生更改时才执行。之后，该函数存储更新后的按钮值。

import tkinter as tk


def on_choice():
    # set prev_btn  as a global so this function can modify its value
    global prev_btn
    # only trigger the useful stuff if the button is different from last time
    if radiobutton_variable.get() != prev_btn:
        print('Function executed')
        # store the value of the most recently pressed button
        prev_btn = radiobutton_variable.get()


root = tk.Tk()
root.geometry('300x150')

radiobutton_variable = tk.StringVar()
radiobutton_variable.set(1)

# define a variable to store the current button state
# (you could also set this to '1', but doing it this way means you won't have
# to update the default value in two places in case you decide to change it
# above!)
prev_btn = radiobutton_variable.get()

button_1 = tk.Radiobutton(root, text='Button 1', variable=radiobutton_variable, value=1, command=on_choice)
button_2 = tk.Radiobutton(root, text='Button 2', variable=radiobutton_variable, value=2, command=on_choice)

button_1.pack()
button_2.pack()

root.mainloop()