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Merge pull request faif#211 from lucasloisp/short-descriptions
Add short descriptions to Abstract Factory, Builder and ObjectPool
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‎creational/abstract_factory.py‎

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#!/usr/bin/env python
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# -*- coding: utf-8 -*-
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# http://ginstrom.com/scribbles/2007/10/08/design-patterns-python-style/
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"""
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*What is this pattern about?
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The Abstract Factory Pattern serves to provide an interface for
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creating related/dependent objects without need to specify their
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actual class.
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The idea is to abstract the creation of objects depending on business
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logic, platform choice, etc.
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*What does this example do?
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This particular implementation abstracts the creation of a pet and
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does so depending on the AnimalFactory we chose (Dog or Cat)
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This works because both Dog/Cat and their factories respect a common
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interface (.speak(), get_pet() and get_food()).
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Now my application can create pets (and feed them) abstractly and decide later,
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based on my own criteria, dogs over cats.
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The second example allows us to create pets based on the string passed by the
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user, using cls.__subclasses__ (the list of sub classes for class cls)
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and sub_cls.__name__ to get its name.
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*Where is the pattern used practically?
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*References:
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https://sourcemaking.com/design_patterns/abstract_factory
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http://ginstrom.com/scribbles/2007/10/08/design-patterns-python-style/
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"""
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"""Implementation of the abstract factory pattern"""
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import six
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import abc
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import random

‎creational/builder.py‎

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# -*- coding : utf-8 -*-
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"""
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*What is this pattern about?
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It decouples the creation of a complex object and its representation,
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so that the same process can be reused to build objects from the same
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family.
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This is useful when you must separate the specification of an object
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from its actual representation (generally for abstraction).
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*What does this example do?
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This particular example uses a Director to abtract the
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construction of a building. The user specifies a Builder (House or
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Flat) and the director specifies the methods in the order necessary
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creating a different building dependding on the sepcified
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specification (through the Builder class).
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@author: Diogenes Augusto Fernandes Herminio <diofeher@gmail.com>
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https://gist.github.com/420905#file_builder_python.py
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*Where is the pattern used practically?
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*References:
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https://sourcemaking.com/design_patterns/builder
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"""
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‎creational/pool.py‎

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# -*- coding: utf-8 -*-
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"""
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*What is this pattern about?
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This pattern is used when creating an object is costly (and they are
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created frequently) but only a few are used at a time. With a Pool we
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can manage those instances we have as of now by caching them. Now it
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is possible to skip the costly creation of an object if one is
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available in the pool.
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A pool allows to 'check out' an inactive object and then to return it.
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If none are available the pool creates one to provide without wait.
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*What does this example do?
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In this example queue.Queue is used to create the pool (wrapped in a
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custom ObjectPool object to use with the with statement), and it is
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populated with strings.
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As we can see, the first string object put in "yam" is USED by the
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with statement. But because it is released back into the pool
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aftwerwards it is reused by the explicit call to sample_queue.get().
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Same thing happens with "sam", when the ObjectPool created insided the
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function is deleted (by the GC) and the object is returned.
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*Where is the pattern used practically?
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*References:
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http://stackoverflow.com/questions/1514120/python-implementation-of-the-object-pool-design-pattern
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https://sourcemaking.com/design_patterns/object_pool
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"""
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class ObjectPool(object):
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def __init__(self, queue, auto_get=False):

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