A simple Tkinter calendar with memo feature

MyCal.py

#!/usr/bin/env python2

import calendar
import datetime
import os.path
from Tkinter import *


class Application(Frame):
    def __init__(self, master):
        Frame.__init__(self, master) 
        self.master = master
        today = datetime.date.today()
        self.year, self.month = today.year, today.month
        btn_prev = Button(self, text='<', command=self.do_prev)
        btn_prev.grid(row=0, column=0, sticky='nesw')
        btn_next = Button(self, text='>', command=self.do_next)
        btn_next.grid(row=0, column=6, sticky='nesw')
        for day_idx, day_name in [
            (0, 'Sun'), (1, 'Mon'), (2, 'Tue'), (3, 'Wed'), (4, 'Thu'), (5, 'Fri'), (6, 'Sat')
        ]:
            lbl_weekday = Label(self, text=day_name)
            lbl_weekday.grid(row=1, column=day_idx, sticky='nesw')
        self.elements = []
        self.draw_calendar()
        self.pack(expand=True)
        self.memo = Memo(self)

    def draw_calendar(self):
        for element in self.elements:
            element.grid_forget()
        self.elements = []
        lbl_date = Label(self, text='%s %d' % ([
            'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'
        ][self.month-1], self.year))
        lbl_date.grid(row=0, column=1, columnspan=5, sticky='nesw')
        self.elements.append(lbl_date)
        cal = calendar.Calendar()
        for week_idx, week in enumerate(cal.monthdatescalendar(self.year, self.month)):
            for day_idx, day in enumerate(week):
                if day.month == self.month:
                    el_date = Button(self, text=day.day, command=lambda date=day: self.memo.show(date))
                else:
                    el_date = Label(self, text=day.day)
                if os.path.isfile('memo-%s.txt' % day):
                    el_date['text'] = '[%d]' % day.day
                el_date.grid(row=week_idx+2, column=day_idx, sticky='nesw')
                self.elements.append(el_date)

    def do_prev(self):
        self.month -= 1
        if self.month == 0:
            self.year -= 1
            self.month = 12
        self.draw_calendar()

    def do_next(self):
        self.month += 1
        if self.month == 13:
            self.year += 1
            self.month = 1
        self.draw_calendar()


class Memo(Frame):
    def __init__(self, app):
        Frame.__init__(self, app.master)
        self.app = app
        self.txt_edit = Text(self)
        self.txt_edit.pack(side=TOP)
        self.btn_ok = Button(self, text='OK', command=self.submit)
        self.btn_ok.pack(side=BOTTOM)

    def show(self, date):
        self.date = date
        self.txt_edit.delete('1.0', 'end')
        try:
            f = open('memo-%s.txt' % date, 'rb')
            text = f.read().decode('utf-8', 'replace')
            f.close()
        except Exception:
            text = ''
        self.txt_edit.insert('1.0', text)
        app.pack_forget()
        self.pack(expand=True)
        self.txt_edit.focus()

    def submit(self):
        self.pack_forget()
        self.app.pack(expand=True)
        text = self.txt_edit.get('1.0', 'end').strip()
        try:
            if text != '':
                f = open('memo-%s.txt' % self.date, 'wb')
                f.write(text.encode('utf-8', 'replace'))
                f.close()
            else:
                os.remove('memo-%s.txt' % self.date)
        except Exception:
            pass
        self.app.draw_calendar()


if __name__ == '__main__':
    root = Tk()
    app = Application(root)
    app.mainloop()