Merge pull request #1 from faif/master

Pull from upstream.

Author: marlboromoo

.gitignore

@@ -0,0 +1 @@
+__pycache__

.travis.yml

@@ -0,0 +1,33 @@
+# vim ft=yaml
+# travis-ci.org definition for python-patterns build
+language: python
+
+sudo: false
+
+python:
+  - "2.7"
+  - "3.3"
+  - "3.4"
+  - "3.5"
+# Disabled for now since cause more pain than gain
+#  - "pypy"
+#  - "pypy3"
+
+cache:
+  - pip
+
+install:
+  - travis_retry pip install -q coveralls codecov
+  - pip install flake8  # eventually worth
+
+script:
+  # Run tests
+  - PYTHONPATH=. nosetests -s -v --with-doctest --with-cov --cover-package . --logging-level=INFO -v .
+  # Actually run all the scripts, contributing to coverage
+  - ./run_all.sh
+  # for now failure in flaking is ignored
+  - flake8 *py || echo "PEP8 the code"
+
+after_success:
+  - coveralls
+  - codecov

3-tier.py

@@ -3,27 +3,33 @@
 
 
 class Data(object):
+    """ Data Store Class """
 
     products = {
         'milk': {'price': 1.50, 'quantity': 10},
         'eggs': {'price': 0.20, 'quantity': 100},
         'cheese': {'price': 2.00, 'quantity': 10}
     }
 
+    def __get__(self, obj, klas):
+        print("(Fetching from Data Store)")
+        return {'products': self.products}
+
 
 class BusinessLogic(object):
+    """ Business logic holding data store instances """
 
-    def __init__(self):
-        self.data = Data()
+    data = Data()
 
     def product_list(self):
-        return self.data.products.keys()
+        return self.data['products'].keys()
 
     def product_information(self, product):
-        return self.data.products.get(product, None)
+        return self.data['products'].get(product, None)
 
 
 class Ui(object):
+    """ UI interaction class """
 
     def __init__(self):
         self.business_logic = BusinessLogic()
@@ -36,20 +42,42 @@ def get_product_list(self):
 
     def get_product_information(self, product):
         product_info = self.business_logic.product_information(product)
-        if product_info is not None:
+        if product_info:
             print('PRODUCT INFORMATION:')
-            print('Name: %s, Price: %.2f, Quantity: %d\n' %
-                  (product.title(), product_info.get('price', 0),
-                   product_info.get('quantity', 0)))
+            print('Name: {0}, Price: {1:.2f}, Quantity: {2:}'.format(
+                product.title(), product_info.get('price', 0),
+                product_info.get('quantity', 0)))
         else:
-            print('That product "%s" does not exist in the records' % product)
-
+            print('That product "{0}" does not exist in the records'.format(
+                product))
 
-if __name__ == '__main__':
 
+def main():
     ui = Ui()
     ui.get_product_list()
     ui.get_product_information('cheese')
     ui.get_product_information('eggs')
     ui.get_product_information('milk')
     ui.get_product_information('arepas')
+
+if __name__ == '__main__':
+    main()
+
+### OUTPUT ###
+# PRODUCT LIST:
+# (Fetching from Data Store)
+# cheese
+# eggs
+# milk
+# 
+# (Fetching from Data Store)
+# PRODUCT INFORMATION:
+# Name: Cheese, Price: 2.00, Quantity: 10
+# (Fetching from Data Store)
+# PRODUCT INFORMATION:
+# Name: Eggs, Price: 0.20, Quantity: 100
+# (Fetching from Data Store)
+# PRODUCT INFORMATION:
+# Name: Milk, Price: 1.50, Quantity: 10
+# (Fetching from Data Store)
+# That product "arepas" does not exist in the records

README.md

@@ -1,4 +1,64 @@
 python-patterns
 ===============
 
-A collection of design patterns implemented (by other people) in python
+A collection of design patterns and idioms in Python.
+
+When an implementation is added or modified, be sure to update this file and
+rerun `append_output.sh` (eg. ./append_output.sh borg.py) to keep the output
+comments at the bottom up to date.
+
+Current Patterns:
+
+__Creational Patterns__:
+
+| Pattern | Description |
+|:-------:| ----------- |
+| [abstract_factory](abstract_factory.py) | use a generic function with specific factories |
+| [borg](borg.py) | a singleton with shared-state among instances |
+| [builder](builder.py) | instead of using multiple constructors, builder object receives parameters and returns constructed objects |
+| [factory_method](factory_method.py) | delegate a specialized function/method to create instances |
+| [lazy_evaluation](lazy_evaluation.py) | lazily-evaluated property pattern in Python |
+| [pool](pool.py) | preinstantiate and maintain a group of instances of the same type |
+| [prototype](prototype.py) | use a factory and clones of a prototype for new instances (if instantiation is expensive) |
+
+__Structural Patterns__:
+
+| Pattern | Description |
+|:-------:| ----------- |
+| [3-tier](3-tier.py) | data<->business logic<->presentation separation (strict relationships) |
+| [adapter](adapter.py) | adapt one interface to another using a white-list |
+| [bridge](bridge.py) | a client-provider middleman to soften interface changes |
+| [composite](composite.py) | encapsulate and provide access to a number of different objects |
+| [decorator](decorator.py) | wrap functionality with other functionality in order to affect outputs |
+| [facade](facade.py) | use one class as an API to a number of others |
+| [flyweight](flyweight.py) | transparently reuse existing instances of objects with similar/identical state |
+| [front_controller](front_controller.py) | single handler requests coming to the application |
+| [mvc](mvc.py) | model<->view<->controller (non-strict relationships) |
+| [proxy](proxy.py) | an object funnels operations to something else |
+
+__Behavioral Patterns__:
+
+| Pattern | Description |
+|:-------:| ----------- |
+| [chain](chain.py) | apply a chain of successive handlers to try and process the data |
+| [catalog](catalog.py) | general methods will call different specialized methods based on construction parameter |
+| [chaining_method](chaining_method.py) | continue callback next object method |
+| [command](command.py) | bundle a command and arguments to call later |
+| [mediator](mediator.py) | an object that knows how to connect other objects and act as a proxy |
+| [memento](memento.py) | generate an opaque token that can be used to go back to a previous state |
+| [observer](observer.py) | provide a callback for notification of events/changes to data |
+| [publish_subscribe](publish_subscribe.py) | a source syndicates events/data to 0+ registered listeners |
+| [registry](registry.py) | keep track of all subclasses of a given class |
+| [specification](specification.py) |  business rules can be recombined by chaining the business rules together using boolean logic |
+| [state](state.py) | logic is organized into a discrete number of potential states and the next state that can be transitioned to |
+| [strategy](strategy.py) | selectable operations over the same data |
+| [template](template.py) | an object imposes a structure but takes pluggable components |
+| [visitor](visitor.py) | invoke a callback for all items of a collection |
+
+
+__Others__:
+
+| Pattern | Description |
+|:-------:| ----------- |
+| [blackboard](blackboard.py) | (architectural model, assemble different sub-system knowledge to build a solution, AI approach - non gang of four pattern) |
+| [graph_search](graph_search.py) | (graphing algorithms, not design patterns) |

__init__.py

@@ -1,3 +1,6 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
 # http://ginstrom.com/scribbles/2007/10/08/design-patterns-python-style/
 
 """Implementation of the abstract factory pattern"""
@@ -6,27 +9,27 @@
 
 
 class PetShop:
+
     """A pet shop"""
 
     def __init__(self, animal_factory=None):
-        """pet_factory is our abstract factory.
-        We can set it at will."""
+        """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"""
+        """Creates and shows a pet using the abstract factory"""
 
         pet = self.pet_factory.get_pet()
-        print("This is a lovely", pet)
-        print("It says", pet.speak())
-        print("It eats", self.pet_factory.get_food())
+        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"
 
@@ -35,6 +38,7 @@ def __str__(self):
 
 
 class Cat:
+
     def speak(self):
         return "meow"
 
@@ -45,6 +49,7 @@ def __str__(self):
 # Factory classes
 
 class DogFactory:
+
     def get_pet(self):
         return Dog()
 
@@ -53,6 +58,7 @@ def get_food(self):
 
 
 class CatFactory:
+
     def get_pet(self):
         return Cat()
 
@@ -68,8 +74,21 @@ def get_factory():
 
 # Show pets with various factories
 if __name__ == "__main__":
-    shop = PetShop()
     for i in range(3):
-        shop.pet_factory = get_factory()
+        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
+# ====================

__pycache__/facade.cpython-33.pyc

@@ -1,6 +1,7 @@
-# http://ginstrom.com/scribbles/2008/11/06/generic-adapter-class-in-python/
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
 
-import os
+"""http://ginstrom.com/scribbles/2008/11/06/generic-adapter-class-in-python/"""
 
 
 class Dog(object):
@@ -32,7 +33,7 @@ def __init__(self):
         self.name = "Car"
 
     def make_noise(self, octane_level):
-        return "vroom%s" % ("!" * octane_level)
+        return "vroom{0}".format("!" * octane_level)
 
 
 class Adapter(object):
@@ -41,32 +42,69 @@ class Adapter(object):
     Usage:
     dog = Dog
     dog = Adapter(dog, dict(make_noise=dog.bark))
+
+    >>> objects = []
+    >>> dog = Dog()
+    >>> print(dog.__dict__)
+    {'name': 'Dog'}
+    >>> objects.append(Adapter(dog, make_noise=dog.bark))
+    >>> print(objects[0].original_dict())
+    {'name': 'Dog'}
+    >>> cat = Cat()
+    >>> objects.append(Adapter(cat, make_noise=cat.meow))
+    >>> human = Human()
+    >>> objects.append(Adapter(human, make_noise=human.speak))
+    >>> car = Car()
+    >>> car_noise = lambda: car.make_noise(3)
+    >>> objects.append(Adapter(car, make_noise=car_noise))
+
+    >>> for obj in objects:
+    ...     print('A {} goes {}'.format(obj.name, obj.make_noise()))
+    A Dog goes woof!
+    A Cat goes meow!
+    A Human goes 'hello'
+    A Car goes vroom!!!
     """
-    def __init__(self, obj, adapted_methods):
+
+    def __init__(self, obj, **adapted_methods):
         """We set the adapted methods in the object's dict"""
         self.obj = obj
         self.__dict__.update(adapted_methods)
 
     def __getattr__(self, attr):
         """All non-adapted calls are passed to the object"""
         return getattr(self.obj, attr)
-
+        
+    def original_dict(self):
+        """Print original object dict"""
+        return self.obj.__dict__
 
 def main():
     objects = []
     dog = Dog()
-    objects.append(Adapter(dog, dict(make_noise=dog.bark)))
+    print(dog.__dict__)
+    objects.append(Adapter(dog, make_noise=dog.bark))
+    print(objects[0].__dict__)
+    print(objects[0].original_dict())
     cat = Cat()
-    objects.append(Adapter(cat, dict(make_noise=cat.meow)))
+    objects.append(Adapter(cat, make_noise=cat.meow))
     human = Human()
-    objects.append(Adapter(human, dict(make_noise=human.speak)))
+    objects.append(Adapter(human, make_noise=human.speak))
     car = Car()
-    car_noise = lambda: car.make_noise(3)
-    objects.append(Adapter(car, dict(make_noise=car_noise)))
+    objects.append(Adapter(car, make_noise=lambda: car.make_noise(3)))
 
     for obj in objects:
-        print("A", obj.name, "goes", obj.make_noise())
+        print("A {0} goes {1}".format(obj.name, obj.make_noise()))
 
 
 if __name__ == "__main__":
     main()
+
+### OUTPUT ###
+# {'name': 'Dog'}
+# {'make_noise': <bound method Dog.bark of <__main__.Dog object at 0x7f631ba3fb00>>, 'obj': <__main__.Dog object at 0x7f631ba3fb00>}
+# {'name': 'Dog'}
+# A Dog goes woof!
+# A Cat goes meow!
+# A Human goes 'hello'
+# A Car goes vroom!!!