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

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

3.输出订单信息保存在deliveries.txt中

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