# 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 {}".format(pet))

print("It says {}".format(pet.speak()))

print("It eats {}".format(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)