83 lines
2.4 KiB
Python
83 lines
2.4 KiB
Python
# 第 3-5 课参考示例：小型仓库领域模型
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#
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# 本示例使用与综合项目不同的“仓库”场景，演示如何让对象各自负责自己的数据和行为。
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# 综合项目仍需独立完成，不能直接复制本示例得到答案。
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from dataclasses import dataclass, field
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class InventoryError(Exception):
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"""表示仓库业务规则错误。"""
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@dataclass
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class Product:
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"""保存商品数据，并负责与商品自身有关的显示。"""
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code: str
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name: str
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quantity: int = 0
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def __post_init__(self) -> None:
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"""确保创建商品时库存数量合法。"""
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if self.quantity < 0:
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raise InventoryError("库存数量不能小于 0。")
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@property
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def in_stock(self) -> bool:
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"""根据当前数量计算是否有库存。"""
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return self.quantity > 0
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def __str__(self) -> str:
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"""返回面向使用者的商品信息。"""
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return f"{self.name}｜库存：{self.quantity}"
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@dataclass
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class Warehouse:
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"""通过组合管理多个 Product 对象。"""
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name: str
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products: dict[str, Product] = field(default_factory=dict)
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def add_product(self, product: Product) -> None:
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"""添加商品，商品编码重复时阻止操作。"""
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if product.code in self.products:
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raise InventoryError("商品编码已存在。")
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self.products[product.code] = product
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def remove_stock(self, code: str, quantity: int) -> None:
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"""扣减指定商品库存。"""
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if code not in self.products:
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raise InventoryError("商品不存在。")
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product = self.products[code]
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if quantity <= 0:
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raise InventoryError("出库数量必须大于 0。")
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if product.quantity < quantity:
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raise InventoryError("库存不足。")
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product.quantity -= quantity
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def main() -> None:
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"""运行仓库领域模型示例。"""
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warehouse = Warehouse("教学仓库")
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keyboard = Product("P001", "机械键盘", 3)
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warehouse.add_product(keyboard)
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print(keyboard)
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print(f"是否有库存：{keyboard.in_stock}")
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warehouse.remove_stock("P001", 2)
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print(f"出库后：{keyboard}")
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try:
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warehouse.remove_stock("P001", 2)
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except InventoryError as error:
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print(f"业务操作失败：{error}")
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if __name__ == "__main__":
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main()
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