python-ui之tkinter初步学习-制作自动更新时间的闹钟

# 引入模块
import tkinter as tk
import time 
# 设计一个时钟类
class clock(tk.Frame):
    wait_time=1000
    def __init__(self, parent=None, **kw):
        tk.Frame.__init__(self, parent, kw)
        self.time_str=tk.StringVar()
        tk.Label(self, textvariable = self.time_str).pack()
    def _update(self):
        self.time_str.set(time.strftime('%Y-%m-%d %H:%M:%S',time.localtime(time.time())))
        self.timer = self.after(self.wait_time, self._update)
    def start(self):
        self._update()
        self.pack(side = tk.TOP)
def main():
    root = tk.Tk()
    mw = clock(root)
    mywatch = tk.Button(root, text = '时钟', command = mw.start)
    mywatch.pack(side = tk.LEFT)
    root.mainloop()
main()