It provides a common interface to create multiple interrelated objects.
Abstract factory pattern intended to: provide an interface to the client, you can create multiple product family products object. However, using the abstract factory is conditional:
1. The system has multiple product family, but once the system is only possible where a family of consumer products
2. The products belong to the same family of products used together , the constraints must be reflected in the design of the system.
Define two classes, Dog and Cat, have speak method
class Dog(object):
def speak(self):
return "woof"
def __str__(self):
return "Dog"
class Cat(object):
def speak(self):
return "meow"
def __str__(self):
return "Cat"Write an abstract factory class PetShop.
class PetShop(object):
"""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()
print("We have a lovely {}".format(pet))
print("It says {}".format(pet.speak()))During initialization, pass a Dog or Cat, after just an ordinary call is the same. show_pet, the initialization of the incoming class.
cat_shop = PetShop(Cat)
cat_shop.show_pet()The complete code is as follows:
import random
class PetShop(object):
"""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()
print("We have a lovely {}".format(pet))
print("It says {}".format(pet.speak()))
class Dog(object):
def speak(self):
return "woof"
def __str__(self):
return "Dog"
class Cat(object):
def speak(self):
return "meow"
def __str__(self):
return "Cat"
# Additional factories:
# Create a random animal
def random_animal():
"""Let's be dynamic!"""
return random.choice([Dog, Cat])()
# Show pets with various factories
if __name__ == "__main__":
# A Shop that sells only cats
cat_shop = PetShop(Cat)
cat_shop.show_pet()
print("")
# A shop that sells random animals
shop = PetShop(random_animal)
for i in range(3):
shop.show_pet()
print("=" * 20)