python之shelve

#!/usr/bin/env python

# database.py

import sys, shelve

def store_person(db):

    """

    Query user for data and store it in the shelf object

    """

    pid = raw_input('Enter unique ID number: ')

    person = {}

    person['name']  = raw_input('Enter name: ')

    person['age']  = raw_input('Enter age: ')

    person['phone'] = raw_input('Enter phone number: ')

    db[pid] = person

def lookup_person(db):

    """

    Query user for ID and desired field, and fetch the corresponding data from

    the shelf object

    """

    pid = raw_input('Enter ID number: ')

    field = raw_input('What would you like to know? (name, age, phone)  ')

    field = field.strip().lower()

    print field.capitalize() + ':', \

          db[pid][field]

def print_help():

    print 'The available commands are:'

    print 'store  : Stores information about a person'

    print 'lookup : Looks up a person from ID number'

    print 'quit   : Save changes and exit'

    print '?      : Prints this message'

def enter_command():

    cmd = raw_input('Enter command (? for help): ')

    cmd = cmd.strip().lower()

    return cmd

def main():

    database = shelve.open('/root/ff/database.dat') # You may want to change this name

    try:

        while True:

            cmd = enter_command()

            if   cmd == 'store':

                store_person(database)

            elif cmd == 'lookup':

                lookup_person(database)

            elif cmd == '?':

                print_help()

            elif cmd == 'quit':

                return

    finally:

        database.close()

if __name__ == '__main__': main()

在主程序main函数中，只有在if __name__=''__main__"条件成立到时候才被调用，这意味着可以在其他程序中将这个程序作为模块导入，然后调用main函数。

main函数使用shelve打开数据库文件。使用strip和lower函数出去空格和使字母为小写字母，使用capitalize()使首字母大写，使用try/finally确保数据库能够正确关闭，不会出现异常。