面向对象
设计模式
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简单工厂模式
设计一个商品类和苹果手机类，同时设计一个苹果手机专卖店类。苹果手机专卖店类可以下订单和出售手机。运行效果
ip=IphoneShop() ip.order() ip.order() ip.order() print('库存中共有:',IphoneShop.iphone_count,'台手机') ip.sail() ip.sail() ip.sail() ip.sail() 运行结果： iphone X 正在出库 iphone X 正在出库 iphone X 正在出库 库存中共有: 3 台手机 售出一台手机，库存还有2台手机 售出一台手机，库存还有1台手机 售出一台手机，库存还有0台手机 手机已经售完！！请进货代码如下
class Goods(object): def __init__(self,brand,price): self.price=price self.brand=brand def outGoods(self): print(self.brand,'正在出库') class Iphone(Goods): def __init__(self,brand,price,name): super(Iphone, self).__init__(brand,price) self.name=name print(self.name, '正在出库') def outGoods(self): print(self.name,'正在出库') class Sasung(Goods): def __init__(self,brand,price,name,pencil): super(Sasung, self).__init__(brand,price) self.name=name self.pencil=pencil print(self.name, '正在出库') def outGoods(self): print(self.name,'正在出库') def createMobile(brand): if brand=='apple': return Iphone('apple',5600,'iphone X') elif brand=='sasung': return Sasung('sasung',4600,'galaxy s6','black pencil') class IphoneShop(object): iphone_count = 0 def __init__(self): self.iphone_count = 0 def order(self): IphoneShop.iphone_count += 1 return createMobile('apple') def sail(self): if IphoneShop.iphone_count>0: IphoneShop.iphone_count -= 1 print('售出一台手机，库存还有{0}台手机'.format(IphoneShop.iphone_count)) else: print('手机已经售完！！请进货') ip=IphoneShop() ip.order() ip.order() ip.order() print('库存中共有:',IphoneShop.iphone_count,'台手机') ip.sail() ip.sail() ip.sail() ip.sail()工厂模式：
class Goods(object): def __init__(self,brand,price): self.price=price self.brand=brand def outGoods(self): print(self.brand,'正在出库') class Iphone(Goods): def __init__(self,brand,price,name): super(Iphone, self).__init__(brand,price) self.name=name print(self.name, '正在出库') class Sasung(Goods): def __init__(self,brand,price,name,pencil): super(Sasung, self).__init__(brand,price) self.name=name self.pencil=pencil print(self.name, '正在出库') # def createMobile(brand): # if brand=='apple': # return Iphone('apple',5600,'iphone X') # elif brand=='sasung': # return Sasung('sasung',4600,'galaxy s6','black pencil') class MobileFactory(object): def createMobile(self,brand): if brand=='apple': return Iphone('apple',5600,'iphone X') elif brand=='sasung': return Sasung('sasung',4600,'galaxy s6','black pencil') class Shop(object): iphone_count = 0 def __init__(self): self.factory=MobileFactory() def order(self,brand): IphoneShop.iphone_count += 1 return self.factory.createMobile(brand) def sail(self): if IphoneShop.iphone_count>0: IphoneShop.iphone_count -= 1 print('售出一台手机，库存还有{0}台手机'.format(IphoneShop.iphone_count)) else: print('手机已经售完！！请进货') ip=Shop() ip.order('apple') ip.order('sasung') ip.order('apple') print('库存中共有:',IphoneShop.iphone_count,'台手机') ip.sail() ip.sail() ip.sail() ip.sail() -
工厂方法模式
简单工厂模式中MobileFactory对象由Shop类初始化来创建，这就决定了Shop只能创建MobileFactory对象。我们把MobileFactory对象交给Shop子类来创建，这样就扩展了Shop的功能。如下：class Shop(object): def createGoods(self,brand): pass def order(self,brand): pass def sail(self): pass class MobileShop(Shop): Mobile_count=0 def createGoods(self,brand): MobileShop.Mobile_count +=1 return MobileFactory().createMobile(brand) def order(self,brand): mobile=self.createGoods(brand) print(mobile.name,'手机到货，库存为', MobileShop.Mobile_count) return mobile def sail(self): if MobileShop.Mobile_count>0: MobileShop.Mobile_count -= 1 print('售出一台手机，库存还有{0}台手机'.format(MobileShop.Mobile_count)) else: print('手机已经售完！！请进货') ip=MobileShop() ip.order('apple') ip.order('sasung') ip.order('apple') ip.sail() ip.sail() ip.sail() ip.sail() -
单例模式预备 new
__new__()必须要有返回值，返回实例化出来的实例，需要注意的是，可以return父类__new__()出来的实例，也可以直接将object的__new__()出来的实例返回。
init()有一个参数self，该self参数就是new()返回的实例，init()在new()的基础上可以完成一些其它初始化的动作，init()不需要返回值。
若new()没有正确返回当前类cls的实例，那init()将不会被调用，即使是父类的实例也不行
我们可以将类比作制造商，new()方法就是前期的原材料购买环节，init()方法就是在有原材料的基础上，加工，初始化商品环节。
class A(object): def __new__(cls, name,age): print('new') return object.__new__(cls) def __init__(self,name,age): self.name=name self.age=age a1=A('tom',12) a2=A('tt',16) a3=A('ff',16) -
单例模式
class A(object): __instance=None __first=False def __new__(cls, name,age): if not cls.__instance: cls.__instance=object.__new__(cls) return cls.__instance def __init__(self,name,age): if not A.__first: self.name=name self.age=age A.__first=True a1=A('tom',12) a2=A('tt',16) a3=A('ff',16) print(id(a1))
