[原创]我的第一个python程序

python简明教程说的，写出这个就可以自称是python程序员了，哈哈
那个判断文件是不是空的方法没找到，写的不优雅
#Filename : addressbook.py
import cPickle as p
class AddressBook:
    def __init__(self, filename):
        self._filename=filename
        f=file(self._filename)
        if f.read:
            self._person_list=p.load(f)
        self._modified = False
        f.close()
        
    def _input_item(self,person_name):
        phone_number=raw_input("Phone number:")
        email=raw_input("Email address:")
        self._person_list[person_name]=[phone_number,email]
        
    def add(self):
        person_name=raw_input("Name:")
        if person_name in self._person_list:
            print "%s has in the address book"%person_name
            return None
        self._input_item(person_name)
        self._modified = True
    def edit(self):
        person_name = raw_input("Name:")
        if not person_name in self._person_list:
            print "%s has not in address book"%person_name
        self._input_item(person_name)
        self._modified = True
        
    def find(self):
        person_name=raw_input("Name to find:")
        if person_name in self._person_list:
            print person_name,self._person_list[person_name]
    def delete(self):
        person_name = raw_input("Name:")
        if not person_name in self._person_list:
            print "%s has not in address book"%person_name
            return None
        del self._person_list[person_name]
        self._modified = True
        
    def show_all(self):
        for item in self._person_list:
            print item,self._person_list[item]
    def get_modified(self):
        return self._modified
   
    def save_all(self):
        f=file(self._filename,'w')
        p.dump(self._person_list,f)
        f.close()
        self._modified = False
        
    _person_list ={}
   
        
class Person:
    def add(self,info):
        self.info = info
def print_usage():
    print "option:"
    print "a : add a person"
    print "e : edit a person"
    print "f : find a person"
    print "d : delete a person"
    print "l : list all people"
    print "s : save the changed"
    print "q : quit address book"
print_usage()
command = raw_input("enter your command #>")
address_book = AddressBook("data")
while command != "q":
    if(command == "a"):
        address_book.add()
    elif(command =="e"):
        address_book.edit()
    elif(command =="f"):
        address_book.find()
    elif(command =="d"):
        address_book.delete()
    elif(command =="l"):
        address_book.show_all()
    elif(command == "s"):
        address_book.save_all()
    else:
        print_usage()
    command = raw_input("enter your command #>")
if address_book.get_modified():
    c=raw_input("Not saved. Save all?(y/n)")
    if(c=="y"):
        address_book.save_all()
print "Good Bye!!"