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#!/usr/bin/env python
# -*- 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("We have a lovely {}".format(pet))
print("It says {}".format(pet.speak()))
print("We also have {}".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__":
for i in range(3):
shop = PetShop(get_factory())
shop.show_pet()
print("=" * 20)
### OUTPUT ###
# We have a lovely Dog
# It says woof
# We also have dog food
# ====================
# We have a lovely Dog
# It says woof
# We also have dog food
# ====================
# We have a lovely Cat
# It says meow
# We also have cat food
# ====================