单例---类方法方式

class Single():
    def __init__(self,name):
        self.name = name
    @classmethod
    def instance(cls,*args,**kwargs):
        if not hasattr(Single,"_instance"):
            Single._instance = Single(*args,**kwargs)
        return Single._instance
s1 = Single.instance('Gage')
s2 = Single.instance()
print(s1)
print(s2)

单例---new方式

class Single(object):
    __isstance = None
    __first_init = False
    def __new__(cls,**kwargs):
        if not cls.__isstance:
            cls.__isstance = object.__new__(cls)
        return cls.__isstance
    def __init__(self,name):
        if not self.__first_init:
            self.name = name
            Singleton.__first_init = True
a = Single('a')
b = Single('b')
print(id(a))
print(id(b))

工厂模式

# 首先定义一个抽象基类
class CarStore(object):
    # 定义生产汽车的方法
    def createcar(self,name):
        pass
    # 根据类型去生产车
    def order(self,name):
        self.car = self.createcar(name)
        self.car.move()
# 定义4s店  实现抽象类
class AoDiCarStore(CarStore):
    def createcar(self,name):
        self.factory = CarFactory()
        return self.factory.createcar(name)
# 创建一个车
class AoDi():
    def move(self):
        print('移动')
# 定义一个工厂
class CarFactory():
    def createcar(self,name):
        self.name = name
        if self.name == 'AoDi':
            self.car = AoDi()
        return self.car
aodi = AoDiCarStore()
aodi.order('AoDi')

本文首发于python黑洞网，博客园同步更新