# http://ginstrom.com/scribbles/2007/10/08/design-patterns-python-style/ """Implementation of the abstract factory pattern""" import random class PetShop: """A pet shop""" def __init__(self, animal_factory=None): """pet_factory is our abstract factory. We can set it at will.""" self.pet_factory = animal_factory def show_pet(self): """Creates and shows a pet using the abstract factory""" pet = self.pet_factory.get_pet() print("This is a lovely", pet) print("It says", pet.speak()) print("It eats", self.pet_factory.get_food()) # Stuff that our factory makes class Dog: def speak(self): return "woof" def __str__(self): return "Dog" class Cat: def speak(self): return "meow" def __str__(self): return "Cat" # Factory classes class DogFactory: def get_pet(self): return Dog() def get_food(self): return "dog food" class CatFactory: def get_pet(self): return Cat() def get_food(self): return "cat food" # Create the proper family def get_factory(): """Let's be dynamic!""" return random.choice([DogFactory, CatFactory])() # Show pets with various factories if __name__ == "__main__": shop = PetShop() for i in range(3): shop.pet_factory = get_factory() shop.show_pet() print("=" * 20)
点击run it 运行之!!!