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'''
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中介者模式（Mediator Pattern）是一种行为型设计模式，它定义了一个中介对象来封装一系列对象之间的交互。
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中介者使各对象不需要显式地相互引用，从而使其耦合松散，而且可以独立地改变它们之间的交互。
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设想书店管理系统，其中包含了多个组件，比如库存管理、订单处理、顾客管理等。
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这些组件之间需要相互通信来协同工作。我们可以使用中介者模式来减少这些组件之间的直接依赖。
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在这个示例中，BookstoreMediator 充当了中介者的角色，它协调了库存管理、订单处理和顾客管理之间的交互。
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当某个事件发生时（比如顾客下订单），相应的组件会通过中介者发送通知，中介者再根据事件类型协调其他组件的响应。
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'''
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from abc import ABC, abstractmethod
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#定义一个中介者接口和具体的中介者实现
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# 中介者接口
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class Mediator(ABC):
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@abstractmethod
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def notify(self, sender, event):
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pass
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# 具体的中介者实现
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class BookstoreMediator(Mediator):
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def __init__(self, inventory, order, customer):
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self.inventory = inventory
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self.order = order
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self.customer = customer
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def notify(self, sender, event):
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if event == 'book_ordered':
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print("BookstoreMediator: Order notification received. Checking inventory...")
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if self.inventory.has_stock():
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print("BookstoreMediator: Inventory has stock. Processing order...")
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self.order.process_order()
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self.customer.notify_order_success()
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else:
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print("BookstoreMediator: Inventory out of stock. Cancelling order...")
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self.order.cancel_order()
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self.customer.notify_order_failure()
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# 可以添加更多的事件处理逻辑
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# 库存管理组件
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class Inventory:
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def has_stock(self):
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# 这里简化逻辑，直接返回有库存
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return True
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# 订单处理组件
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class Order:
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def process_order(self):
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print("Order: Order is being processed...")
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def cancel_order(self):
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print("Order: Order is being cancelled...")
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# 顾客管理组件
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class Customer:
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def notify_order_success(self):
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print("Customer: Order successful. Notifying customer...")
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def notify_order_failure(self):
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print("Customer: Order failed. Notifying customer...")
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# 组件之间的交互通过中介者进行
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class BookstoreComponent:
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def __init__(self, mediator):
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self.mediator = mediator
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def send_notification(self, event):
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self.mediator.notify(self, event)
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# 示例使用
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if __name__ == "__main__":
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# 创建组件
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inventory = Inventory()
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order = Order()
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customer = Customer()
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# 创建中介者并注入组件
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mediator = BookstoreMediator(inventory, order, customer)
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# 创建与中介者关联的书店组件（这里以订单为例）
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order_component = BookstoreComponent(mediator)
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# 触发事件（比如：下订单）
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order_component.send_notification('book_ordered') |
