#!/usr/bin/env python

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

"""

*What is this pattern about?

In Java and other languages, the Abstract Factory Pattern serves to provide an interface for

creating related/dependent objects without need to specify their

actual class.

>>在Java和其他语言中，抽象工厂模式为创建相关联的对象提供借口，而不用制定他们的实体类

The idea is to abstract the creation of objects depending on business

logic, platform choice, etc.

>>这是为了抽象创建基于业务逻辑和用户选择而创建的

In Python, the interface we use is simply a callable, which is "builtin" interface

in Python, and in normal circumstances we can simply use the class itself as

that callable, because classes are first class objects in Python.

>>在python中，我们使用的接口是可调用的，是一个可创建的借口

>>在python中，通常情况下，我们只使用类本身作为可调用的接口，因为类是第一个对象

*What does this example do?

This particular implementation abstracts the creation of a pet and

does so depending on the factory we chose (Dog or Cat, or random_animal)

This works because both Dog/Cat and random_animal respect a common

interface (callable for creation and .speak()).

>>这个抽象的实现了创造一个宠物，然后基于我们选择的工厂类型（狗或者猫或者其他随意的动物）

>>这个可以实现因为猫，狗或者其他的动物都遵照这个接口（可调用创造和说话）

Now my application can create pets abstractly and decide later,

based on my own criteria, dogs over cats.

>>现在我的应用可以抽象创造宠物然后再根据我个人的准早来创造狗，而不是猫

*Where is the pattern used practically?

*References:

https://sourcemaking.com/design_patterns/abstract_factory

http://ginstrom.com/scribbles/2007/10/08/design-patterns-python-style/

*TL;DR80

Provides a way to encapsulate a group of individual factories.

"""

import random

class PetShop(object):

    """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()

        print("We have a lovely {}".format(pet))

        print("It says {}".format(pet.speak()))

class Dog(object):

    def speak(self):

        return "woof"

    def __str__(self):

        return "Dog"

class Cat(object):

    def speak(self):

        return "meow"

    def __str__(self):

        return "Cat"

# Additional factories:

# Create a random animal

def random_animal():

    """Let's be dynamic!"""

    return random.choice([Dog, Cat])()

# Show pets with various factories

if __name__ == "__main__":

    # A Shop that sells only cats

    cat_shop = PetShop(Cat)

    cat_shop.show_pet()

    print("")

    # A shop that sells random animals

    shop = PetShop(random_animal)

    for i in range(3):

        shop.show_pet()

        print("=" * 20)

### OUTPUT ###

# We have a lovely Cat

# It says meow

#

# We have a lovely Dog

# It says woof

# ====================

# We have a lovely Cat

# It says meow

# ====================

# We have a lovely Cat

# It says meow

# ====================