python - Tkinter - 输入框 - 日期格式

Question

我想要一个用于输入日期的输入框，以便用户只能以一种方式输入。

键入前的输入框如下所示(没有下划线)__/__/____，以及 / 不会在用户键入日期时被删除。

谢谢

Answer 1

感谢@Bryan Oakley 的重要提示，我想出了这个工作代码。

(更新:投入了几年的编程经验和一些近期读者对改进代码的敏锐眼光。)

from __future__ import print_function

try:
    import Tkinter as tk
except ImportError:
    import tkinter as tk


class DateEntry(tk.Frame):
    def __init__(self, master, frame_look={}, **look):
        args = dict(relief=tk.SUNKEN, border=1)
        args.update(frame_look)
        tk.Frame.__init__(self, master, **args)

        args = {'relief': tk.FLAT}
        args.update(look)

        self.entry_1 = tk.Entry(self, width=2, **args)
        self.label_1 = tk.Label(self, text='/', **args)
        self.entry_2 = tk.Entry(self, width=2, **args)
        self.label_2 = tk.Label(self, text='/', **args)
        self.entry_3 = tk.Entry(self, width=4, **args)

        self.entry_1.pack(side=tk.LEFT)
        self.label_1.pack(side=tk.LEFT)
        self.entry_2.pack(side=tk.LEFT)
        self.label_2.pack(side=tk.LEFT)
        self.entry_3.pack(side=tk.LEFT)

        self.entries = [self.entry_1, self.entry_2, self.entry_3]

        self.entry_1.bind('<KeyRelease>', lambda e: self._check(0, 2))
        self.entry_2.bind('<KeyRelease>', lambda e: self._check(1, 2))
        self.entry_3.bind('<KeyRelease>', lambda e: self._check(2, 4))

    def _backspace(self, entry):
        cont = entry.get()
        entry.delete(0, tk.END)
        entry.insert(0, cont[:-1])

    def _check(self, index, size):
        entry = self.entries[index]
        next_index = index + 1
        next_entry = self.entries[next_index] if next_index < len(self.entries) else None
        data = entry.get()

        if len(data) > size or not data.isdigit():
            self._backspace(entry)
        if len(data) >= size and next_entry:
            next_entry.focus()

    def get(self):
        return [e.get() for e in self.entries]


if __name__ == '__main__':        
    win = tk.Tk()
    win.title('DateEntry demo')

    dentry = DateEntry(win, font=('Helvetica', 40, tk.NORMAL), border=0)
    dentry.pack()

    win.bind('<Return>', lambda e: print(dentry.get()))
    win.mainloop()