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# 和工厂模式类似，不过这里的结果只是产生不同的类方法
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# 设想书店有多种折扣策略，比如“普通会员折扣”、“金牌会员折扣”和“无折扣”。每种折扣策略都是一个具体的策略实现。
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from abc import ABC, abstractmethod
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########################################################
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# 创建折扣策略接口
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########################################################
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class DiscountStrategy(ABC):
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@abstractmethod
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def calculate_discount(self, book_price):
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pass
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########################################################
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# 创建实现了DiscountStrategy接口的具体折扣策略类
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########################################################
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class NoDiscountStrategy(DiscountStrategy):
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def calculate_discount(self, book_price):
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return book_price # 无折扣，原价返回
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class RegularMemberDiscountStrategy(DiscountStrategy):
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def calculate_discount(self, book_price):
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return book_price * 0.9 # 普通会员9折
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class GoldMemberDiscountStrategy(DiscountStrategy):
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def calculate_discount(self, book_price):
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return book_price * 0.8 # 金牌会员8折
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########################################################
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# 定义Book类和Bookstore类。Book类包含书籍的信息和价格，Bookstore类则使用折扣策略来计算书籍的折后价
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########################################################
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class Book:
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def __init__(self, title, price):
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self.title = title
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self.price = price
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class Bookstore:
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def __init__(self, discount_strategy):
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self.discount_strategy = discount_strategy
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def set_discount_strategy(self, discount_strategy):
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self.discount_strategy = discount_strategy
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def calculate_final_price(self, book):
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discounted_price = self.discount_strategy.calculate_discount(book.price)
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return discounted_price
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if __name__ == "__main__":
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# 创建书籍对象
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book = Book("The Great Gatsby", 30.0)
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# 创建折扣策略对象
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no_discount = NoDiscountStrategy()
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regular_discount = RegularMemberDiscountStrategy()
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gold_discount = GoldMemberDiscountStrategy()
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# 创建书店对象，并设置不同的折扣策略
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bookstore = Bookstore(no_discount)
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print(f"No Discount: The final price of '{book.title}' is {bookstore.calculate_final_price(book)}")
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bookstore.set_discount_strategy(regular_discount)
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print(f"Regular Member Discount: The final price of '{book.title}' is {bookstore.calculate_final_price(book)}")
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bookstore.set_discount_strategy(gold_discount)
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print(f"Gold Member Discount: The final price of '{book.title}' is {bookstore.calculate_final_price(book)}") |
