add an implementation of abstract factory

.travis.yml

@@ -18,7 +18,7 @@ cache:
   - pip
 
 install:
-  - travis_retry pip install -q coveralls codecov
+  - travis_retry pip install -q coveralls codecov six
   - pip install flake8  # eventually worth
 
 script:

creational/abstract_factory.py

@@ -4,7 +4,8 @@
 # http://ginstrom.com/scribbles/2007/10/08/design-patterns-python-style/
 
 """Implementation of the abstract factory pattern"""
-
+import six
+import abc
 import random
 
 
@@ -72,17 +73,46 @@ def get_factory():
     return random.choice([DogFactory, CatFactory])()
 
 
+# Implementation 2 of an abstract factory
+@six.add_metaclass(abc.ABCMeta)
+class Pet(object):
+
+    @classmethod
+    def from_name(cls, name):
+        for sub_cls in cls.__subclasses__():
+            if name == sub_cls.__name__.lower():
+                return sub_cls()
+
+    @abc.abstractmethod
+    def speak(self):
+        """"""
+
+
+class Kitty(Pet):
+    def speak(self):
+        return "Miao"
+
+
+class Duck(Pet):
+    def speak(self):
+        return "Quak"
+
+
 # Show pets with various factories
 if __name__ == "__main__":
     for i in range(3):
         shop = PetShop(get_factory())
         shop.show_pet()
         print("=" * 20)
 
+    for name0 in ["kitty", "duck"]:
+        pet = Pet.from_name(name0)
+        print("{}: {}".format(name0, pet.speak()))
+
 ### OUTPUT ###
-# 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
 # ====================
 # We have a lovely Dog
 # It says woof
@@ -92,3 +122,5 @@ def get_factory():
 # It says meow
 # We also have cat food
 # ====================
+# kitty: Miao
+# duck: Quak

tests/test_abstract_factory.py

@@ -2,7 +2,7 @@
 # -*- coding: utf-8 -*-
 import unittest
 from creational.abstract_factory import PetShop,\
-    Dog, Cat, DogFactory, CatFactory
+    Dog, Cat, DogFactory, CatFactory, Pet
 try:
     from unittest.mock import patch
 except ImportError:
@@ -54,3 +54,12 @@ def test_dog_shall_woof(cls):
 
     def test_dog_shall_be_printable(cls):
         cls.assertEqual(str(cls.d), 'Dog')
+
+
+class PetTest(unittest.TestCase):
+
+    def test_from_name(self):
+        test_cases = [("kitty", "Miao"), ("duck", "Quak")]
+        for name, expected_speech in test_cases:
+            pet = Pet.from_name(name)
+            self.assertEqual(pet.speak(), expected_speech)