这两章节，主要是应用python自带GUI库tkinter 和异常处理机制，实现对名为Head-Ex快递公司的订单写入保存功能。

from tkinter import *
#import tkinter.messagebox

def save_data():#写入订单信息
    try:#用于捕获异常
        fileD = open("deliveries.txt", "a")
        fileD.write("Depot:\n")
        fileD.write("%s\n" % depot.get())
        fileD.write("Description:\n")
        fileD.write("%s\n" % description.get())
        fileD.write("Address:\n")
        fileD.write("%s\n" % address.get("1.0", END))
        depot.set(None)
        description.delete(0, END)
        address.delete("1.0", END)#起始行号1, 起始列号0
    except Exception as ex:#用于处理异常
        tkinter.messagebox.showerror("Error", "Can't write to the file!!!\n%s" % ex)

def read_depots(file):
    depots = [] #空列表
    depots_t = open(file)
    for line in depots_t:
        depots.append(line.strip())
    return depots

app = Tk()
app.title('Head-Ex Deliverlies')
Label(app, text = "Depot:").pack()

depot = StringVar()#可变字符串类型变量depot
depot.set(None)
options = read_depots("depots.txt")#存储已经有的内容
OptionMenu(app, depot, *options).pack()

Label(app, text = "Description:").pack()
description = Entry(app)#多用于单行文本输入
description.pack()

Label(app, text = "Address:").pack()
address = Text(app)#多用于多行文本输入
address.pack()

Button(app, text = "Save", command = save_data).pack()#command相应保存数据函数
app.mainloop()


1. 已知快递仓库信息存储在depots.txt文本中

Cambridge, MA
Cambridge, UK
Seatle, WA
New York, NY
Dallas, TX
Boston, MA
Rome, Italy
Male, Maldives
Luxor, Egypt
Rhodes, Greece
Edinburgh, Scotland

2.GUI运行界面

《Head First Programming》---python 8 and 8 1/2_GUI, data, exception_exception


3.输出订单信息保存在deliveries.txt中

Depot:
 Edinburgh, Scotland
 Description:
 Rose
 Address:
 Flowers Road, Love Street.