python设计模式之工厂模式(Factory Pattern)

python设计模式之工厂模式(Factory Pattern)

工厂模式的本质就是用工厂方法代替new操作创建一种实例化对象的方式.

这里专门定义一个Operation类作为父类，加减乘除运算类继承Operation类，OperationFactory类用来决定什么时候创建对应的类

import randomfrom typing import Typeclass Pet: def __init__(self, name: str) -> None: self.name = name def speak(self) -> None: raise NotImplementedError def __str__(self) -> str: raise NotImplementedErrorclass Dog(Pet): def speak(self) -> None: print("woof") def __str__(self) -> str: return f"Dog<{self.name}>"class Cat(Pet): def speak(self) -> None: print("meow") def __str__(self) -> str: return f"Cat<{self.name}>"class PetShop: """A pet shop""" def __init__(self, animal_factory: Type[Pet]) -> None: """pet_factory is our abstract factory. We can set it at will.""" self.pet_factory = animal_factory def buy_pet(self, name: str) -> Pet: """Creates and shows a pet using the abstract factory""" pet = self.pet_factory(name) print(f"Here is your lovely {pet}") return pet# Additional factories:# Create a random animaldef random_animal(name: str) -> Pet: """Let's be dynamic!""" return random.choice([Dog, Cat])(name)if __name__ == '__main__': cat_shop = PetShop(Cat) pet = cat_shop.buy_pet("Lucy") pet.speak() shop = PetShop(random_animal) for name in ["Max", "Jack", "Buddy"]: pet = shop.buy_pet(name) pet.speak() print("=" * 20)

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