在 Tkinter 中调用更改组合框选项的函数

Question

在下面的代码中，如何在更改时调用函数OptionCallBack并将cm所选选项传递到要显示的消息框中？

import Tkinter
import tkMessageBox
from Tkinter import *
import ttk

app = Tk()
app.configure(background='DimGray')
app.geometry('600x600')
app.resizable(width=False, height=False)

def OptionCallBack():
   tkMessageBox.showinfo( "Selected Phase", "??????")



variable = StringVar(app)
variable.set("Select From List")

cm = ttk.Combobox(app, textvariable=variable)
cm.config(values =('Select From Phase A', 'Select From Phase B'))
cm.pack()

app.mainloop()

Answer 1

对变量使用跟踪：

def OptionCallBack(*args):
   tkMessageBox.showinfo( "Selected Phase", variable.get())

variable = StringVar(app)
variable.set("Select From List")
variable.trace('w', OptionCallBack)