Python 初学笔记：地址簿练习

《简明Python教程》（点击打开链接）里有一个关于地址簿练习的提议，个人觉得很有意思，刚好也练练手。具体实现代码如下：

# Filename: adsbook.py

import cPickle
import os

class Person:
fname = "adsbook.pd"
adslist = {}
def __init__(self, name, age, email, phone):
self.name = name
self.age = age
self.email = email
self.phone = phone
Person.adslist[name] = [age, email, phone]
# print "Name: %s; Age: %s;\nEmail: %s;\nPhone: %s;\n\twas created." \
#      % (name, age, email, phone)
def __del__(self):
# print "%s has been deleted." % self.name
pass

class NameIsNullError(IOError):
def __init__(self, errstr):
IOError.__init__(self)
self.errstr = errstr
print errstr

def Validate(input_str):
if len(input_str) == 0:
return 'Unknow'
else:
return input_str

def Save(adslist, fname):
if len(adslist) >= 1:
f = file(fname, 'w')
cPickle.dump(adslist, f)
f.close()
else:
pass

if os.path.isfile(Person.fname):
f = file(Person.fname)
Person.adslist = cPickle.load(f)
f.close()
else:
pass

flag = True

while flag:
s = raw_input("Enter your option --->")
if s == 'quit':
flag = False
elif s == 'help':
print '''help: help!!!;
quit: quit;
version: version;
add: add a new person;
modify: modify some info.;
del: delete one's info.;
find: find details about s.b.;
save: save the info..
'''
elif s == 'version':
print 'Version 1.0.0'
elif s == 'add' or s == 'modify':
name = raw_input("Name: --->")
if len(name) == 0:
raise NameIsNullError('Error: input name is null')
elif Person.adslist.has_key(name) and s == 'add':
print 'A person called %s has already exists.\
Do you want to update his/her information? (y/n)' % name
if raw_input() == 'n':
continue
else:
pass
age = raw_input("Age: --->")
# age = Validate(age)
email = raw_input("Email: --->")
# email = Validate(email)
phone = raw_input("Phone: --->")
# phone = Validate(phone)
Person(name, age, email, phone)
elif s == 'del':
name = raw_input("Enter the name to be deleted: --->")
if len(name) == 0:
pass
elif Person.adslist.has_key(name):
del Person.adslist[name]
print '%s has been deleted.' % name
else:
print 'The name you entered does not exists.'
elif s == 'find':
name = raw_input("Enter the name you want to find out: --->")
if len(name) == 0:
pass
elif not Person.adslist.has_key(name):
print r"The name you entered doesn't exists."
else:
print "Name: %s; Age: %s;\nEmail: %s;\nPhone: %s;"\
% (name, Person.adslist[name][0], Person.adslist[name][1], \
Person.adslist[name][2])
elif s == 'save':
Save(Person.adslist, Person.fname)
print 'Done'
else:
print 'Unknow option.'

# Save to pickler
Save(Person.adslist, Person.fname)

代码运行起来，暂时感觉效果还可以，以后有机会再做改进。

附：Python类，当创建的新对象与原有对象同名时，会自动删掉原来的对象。或者说当一个对象没有引用时，它就会被立即删掉。例如下面一段程序，对变量p二次赋值时，原有的对象Sinjon就自动调用__del__方法删掉了。

class Person:
population = 0
def __init__(self, name, age):
self.name = name
self.age = age
Person.population += 1
print 'initializing person:\n Name %s Age %s' % (name, age)
def __del__(self):
Person.population -= 1
print 'deleting person:\n name %s' % self.name
def sayHello(self):
print 'Hello, my name is', self.name
def howMany(self):
if Person.population == 1:
print 'I am the only person here.'
else:
print 'We have %d persons here.' % Person.population

p = Person('Sinjon', 25)
p.sayHello()
p.howMany()
p = Person('Candy', 25)
p.sayHello()
p.howMany()

输出：