python怎样实现不用装饰器实现登陆器小程序

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Created on Tue Nov 26 15:26:58 2019

@author: root
"""

def menu():
  print('choice'.center(50,'-'))
  msg = '''
  1. home
  2. finance
  3. book
  4. exit
  '''
  print(msg)
  print("".center(50,'-'))
 
def login(login_flat,choice):
  if not login_flat:
    while True:
      username = str(input("username:"))
      password = str(input("password:"))
      if choice == '1':
        home()
        with open('jingdong.txt','r') as f1:
          for line in f1:
            element = line.split(" ",1)
            print(element[0])
            print(element[1])
            if username.strip() == element[0].strip() and password.strip() == element[1].strip():
              print("log in successful!")
              return True
            print("failed to log in!,try it again!")
      elif choice == '2':
        finance()
        with open('weixin.txt','r') as f2:
          for line in f1:
            element = line.split(" ",1)
            if username.strip() == element[0].strip() and password.strip() == element[1].strip():
              print("log in successful!")
              return True
            print("failed to log in!,try it again!")   
      elif choice == '3':
        book()
        with open('jingdong.txt','r') as f3:
          for line in f3:
            element = line.split(" ",1)
            if username.strip() == element[0].strip() and password.strip() == element[1].strip():
              print("log in successful!")
              return True
            print("failed to log in!,try it again!")              
  else:
    print("You have logged in before!")
    return True
#@login(login_flat,choice)            
def home():
  print("home.....")
#@login(login_flat,choice) 
def finance():
  print("finance.....")
#@login(login_flat,choice) 
def book():
  print("book.....")

  
login_flag = False
while True:
  menu()
  choice = input("your choice:")
  if choice == '1':
    login_flag = login(login_flag,choice)
  elif choice == '2':
    login_flag = login(login_flag,choice)
  elif choice == '3':
    login_flag = login(login_flag,choice)
  elif choice == '4':
    print('bye-bye')
    break
  else:
    print("wrong input ,try it again!")