address_book.py

import os
import pickle # reference: https://wiki.python.org/moin/UsingPickle

#
# Write a program that keeps names and email addresses in a dictionary as key-value pairs.
# Each time the program starts, it should retrieve the dictionary from the file and unpickle it.
#

ADDRESS_BOOK_FILE_NAME = os.path.join(os.path.dirname(__file__), "address_book.p")

if os.path.isfile(ADDRESS_BOOK_FILE_NAME):
    address_book = pickle.load( open(ADDRESS_BOOK_FILE_NAME, "rb" ) ) #> {'lisa': '[email protected]', 'mike': '[email protected]'}
else:
    address_book = {}

#
# The program should display a menu that lets the user:
#   look up a person's email address
#   add a new name and email address
#   change an existing email address
#   delete an existing name and email address
#

def handle_menu_choice(menu_choice):
    print("YOU CHOSE: " + menu_choice)
    if menu_choice == "Create":
        handle_create()
    elif menu_choice == "Read":
        handle_read()
    elif menu_choice == "Update":
        handle_update()
    elif menu_choice == "Destroy":
        handle_destroy()
    else:
      print("TODO: implement handler for " + menu_choice)

def handle_create():
    name = input("Please input the person's name (e.g. 'Rich'):")
    email = input("Please input the person's email (e.g. '[email protected]'):")
    address_book[name] = email

def handle_read():
    name = input("Please input the person's name (e.g. 'Rich'):")
    if name in address_book:
        print("FOUND NAME " + name + " IN ADDRESS BOOK")
        print("EMAIL ADDRESS IS " + address_book[name])
    else:
        print("NAME " + name + " NOT FOUND IN ADDRESS BOOK")

def handle_update():
    name = input("Please input the person's name (e.g. 'Rich'):")
    if name in address_book:
        print("FOUND NAME " + name + " IN ADDRESS BOOK")
        print("EMAIL ADDRESS IS " + address_book[name])
        email = input("Please input the person's new email (e.g. '[email protected]'):")
        address_book[name] = email
    else:
        print("NAME " + name + " NOT FOUND IN ADDRESS BOOK")

def handle_destroy():
    name = input("Please input the person's name (e.g. 'Rich'):")
    if name in address_book:
        print("FOUND NAME " + name + " IN ADDRESS BOOK")
        del address_book[name]
        print("DELETED NAME " + name + " FROM ADDRESS BOOK")
    else:
        print("NAME " + name + " NOT FOUND IN ADDRESS BOOK")

menu = """

ADDRESS BOOK APPLICATION

Please input one of the following commands (e.g. 'Command') then press enter:

    'Create'    add a new name and email address
    'Read'      look up a person's email address
    'Update'    change an existing email address
    'Destroy'   delete an existing name and email address


""" # multiline string http://stackoverflow.com/questions/10660435/pythonic-way-to-create-a-long-multi-line-string ...

menu_choice = input(menu)

handle_menu_choice(menu_choice)

#
# the program should pickle the dictionary and save it to a file when the user exits the program.
#

print(address_book)

print("WRITING TO FILE -- " + ADDRESS_BOOK_FILE_NAME)

pickle.dump(address_book, open(ADDRESS_BOOK_FILE_NAME, "wb" )) # https://wiki.python.org/moin/UsingPickle