python - 将 Tkinter 小部件重置为其默认值

Question

需要创建一个通用函数，在发生事件时它将聚焦的小部件返回到其默认值。有办法实现吗？

例子:

entry1 = Tkinter.Entry()
entry1.grid(..)
entry1.insert(0,"hello")
entry1.bind("<FocusIn>", EntryFocusedIn)
entry1.bind("<FocusOut>", EntryFocusedOut)

entry2 = Tkinter.Entry()
entry2.grid(..)
entry2.insert(0,"again")
entry2.bind("<FocusIn>", EntryFocusedIn)
entry2.bind("<FocusOut>", EntryFocusedOut)  

def EntryFocusedIn(params):
     params.widget.delete(0, Tkinter.END)

def EntryFocusedOut(params):
     # return widget to its default value
     # which in case of entry1 its "hello"
     # and in case of entry2 its "again"

Answer 1

您可以子类化 Entry 小部件以添加一个属性来存储默认值，并在事件处理程序中引用该属性。但是，没有什么可以阻止您直接将自己的属性添加到每个 Entry 小部件，例如entry1.default_value = 'hello'，entry1.default_value = 'again':

import Tkinter

def EntryFocusedIn(params):
    params.widget.delete(0, Tkinter.END)

def EntryFocusedOut(params):
    # restore default value
    params.widget.delete(0, Tkinter.END)
    params.widget.insert(0, params.widget.default_value)

root = Tkinter.Tk()

entry1 = Tkinter.Entry()
entry1.default_value = 'hello'
entry1.pack()
entry1.insert(0, entry1.default_value)
entry1.bind("<FocusIn>", EntryFocusedIn)
entry1.bind("<FocusOut>", EntryFocusedOut)

entry2 = Tkinter.Entry()
entry2.default_value = 'again'
entry2.pack()
entry2.insert(0, entry2.default_value)
entry2.bind("<FocusIn>", EntryFocusedIn)
entry2.bind("<FocusOut>", EntryFocusedOut)

root.mainloop()