"""
Code illustration: 10.06
validate='focusout' demo
Tkinter GUI Application Development Blueprints
"""
import tkinter as tk
import re
class FocusOutValidationDemo():
def __init__(self):
self.master = tk.Tk()
self.error_message = tk.Label(text='', fg='red')
self.error_message.pack()
tk.Label(text='Enter Email Address').pack()
vcmd = (self.master.register(self.validate_email), '%P')
invcmd = (self.master.register(self.invalid_email), '%P')
self.email_entry = tk.Entry(
self.master, validate="focusout", validatecommand=vcmd, invalidcommand=invcmd)
self.email_entry.pack()
tk.Button(self.master, text="Login").pack()
tk.mainloop()
def validate_email(self, P):
self.error_message.config(text='')
x = re.match(r"[^@]+@[^@]+\.[^@]+", P)
return (x != None)
def invalid_email(self, P):
self.error_message.config(text='Invalid Email Address')
self.email_entry.focus_set()
app = FocusOutValidationDemo()
