設計模式之十五--享元模式

享元模式：運用共享技術有效地支持大量細粒度的對象。

享元模式和單例模式類似的地方。共通的思路，就是同一類對象之創建一個實例，享元模式在此基礎上進一步加工。利用工廠模式來返回需要的對象。

from abc import ABCMeta, abstractmethod


class Website(metaclass=ABCMeta):

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

    @abstractmethod
    def use(self, user):
        pass


class ConcreteWebsite(Website):

    def __init__(self, name):
        super().__init__(name)

    def use(self, user):
        print("{0} uses {1}".format(user.name, self.name))


class User:
    def __init__(self, name):
        self.__name = name

    @property
    def name(self):
        return self.__name

    @name.setter
    def name(self, value):
        self.__name = value


class WebsiteFactory:
    def __init__(self):
        self.website = {}

    def get_website(self, website_type):
        if website_type not in self.website.keys():
            self.website[website_type] = ConcreteWebsite(website_type)
        return self.website[website_type]


if __name__ == "__main__":

    user = User("Li")
    web_factory = WebsiteFactory()
    website = web_factory.get_website("Blog")
    website.use(user)

    user.name = "Wang"
    website = web_factory.get_website("Production Demonstration")
    website.use(user