创建型模式

from abc import ABCMeta,abstractmethod

class Payment(metaclass=ABCMeta):
    # abstract class
    @abstractmethod
    def pay(self, money):
        pass

class Alipay(Payment):
    def pay(self, money):
        print("支付宝支付%d元。"%money)
    
class WechatPay(Payment):
    def pay(self, money):
        print("微信支付%d元。"%money)

class PaymentFactory:
    def create_payment(self, method):
        if method == 'alipay':
            return Alipay()
        elif method == 'Wechat':
            return WechatPay()
        else:
            raise TypeError("No such payment named %s" %method)

# client
pf = PaymentFactory()
p = pf.create_payment('alipay')
p.pay(100)

　　

 如果改为：

from abc import ABCMeta,abstractmethod

class Payment(metaclass=ABCMeta):
    # abstract class
    @abstractmethod
    def pay(self, money):
        pass

class Alipay(Payment):
    def __init__(self, use_huabei=False):
        self.use_huabei = use_huabei
    def pay(self, money):
        if self.use_huabei:
            print("花呗支付%d元。"%money)
        else:
            print("支付宝余额支付%d元。"%money)
    
class WechatPay(Payment):
    def pay(self, money):
        print("微信支付%d元。"%money)

class PaymentFactory:
    def create_payment(self, method):
        if method == 'alipay':
            return Alipay()
        elif method == 'Wechat':
            return WechatPay()
        elif method == 'huabei':
            return Alipay(use_huabei=True)
        else:
            raise TypeError("No such payment named %s" %method)

# client
pf = PaymentFactory()
p = pf.create_payment('huabei')
p.pay(100)

隐藏了类的内部实现。