程序设计模式 工厂模式 单立模式

'工厂模式'
class msg(object):

def mail(self,msg):
pass

def sms(self,msg):
pass

def weixin(self,msg):
pass

def sender(self,msg,msg_type):
if msg_type == 'sms':
self.sms(msg)
elif msg_type == 'mail':
self.mail(msg)

import statsout
def output(data, format="text"):
output_function = getattr(statsout, "output_%s" %format)
return output_function(data)

#!/usr/bin/python
# -*- coding: utf-8 -*-

__author__ = 'gaogd'

'''
单立模式
'''
def singletion(cls):
instances = {}

def warpper(*args,**kwargs):
if cls not in instances:
instances[cls] = cls(*args,**kwargs)
return  instances[cls]
return  warpper

@singletion
class Myclass(object):

def __init__(self,n):
self.n = n

c = Myclass('10')
c2 = Myclass('20')

## 装饰器的作用:   @singletion 《=》 Myclass = singletion(Myclass)

# print '--->',c.n ,c2.n

#方法2,实现__new__方法
#并在将一个类的实例绑定到类变量_instance上,
#如果cls._instance为None说明该类还没有实例化过,实例化该类,并返回
#如果cls._instance不为None,直接返回cls._instance
class Singleton(object):
def __new__(cls, *args, **kw):
if not hasattr(cls, '_instance'):   ##如果cls中不包含_instance方法,就执行下面
orig = super(Singleton, cls)     ##继承原始的类
cls._instance = orig.__new__(cls, *args, **kw) ##在这个类上面添加_instance方法
return cls._instance  ##返回这个新类

class MyClass1(Singleton):
a = 1

one = MyClass1()
two = MyClass1()
two.a = 5
print one.a,two.a

### __new__()方法负责生成__init__()方法的