GoF design pattern with Python - AbstractFactory

abstract_factory.py

# -*- coding: utf-8 -*-

# 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)