Python实现工厂模式的两个例子

#!/usr/bin/python
# coding:utf8
'''
Factory Method
'''


class ChinaGetter:
    """A simple localizer a la gettext"""

    def __init__(self):
        self.trans = dict(jianrong=u"杨建荣", jianrong_notes=u"学习笔记")

    def get(self, msgid):
        """We'll punt if we don't have a translation"""
        try:
            return self.trans[msgid]
        except KeyError:
            return str(msgid)


class EnglishGetter:
    """Simply echoes the msg ids"""
    def __init__(self):
        self.trans = dict(jeanron100=u"jeanron100...", mysql=u"MySQL", oracle=u"Oracle")

    def get(self, msgid):
        try:
            return self.trans[msgid]
        except KeyError:
            return str(msgid)


def get_localizer(language="English"):
    """The factory method"""
    languages = dict(English=EnglishGetter, China=ChinaGetter)
    return languages[language]()


# Create our localizers
e, g = get_localizer("English"), get_localizer("China")
# Localize some text
for msgid in "jeanron100 jianrong mysql oracle".split():
    print(e.get(msgid), g.get(msgid))

#!/usr/bin/python
# coding:utf8
'''
Abstract Factory
'''

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("This is a lovely", str(pet))
        print("It says", pet.speak())
        print("It eats", 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__":
    shop = PetShop()
    for i in range(3):
        shop.pet_factory = get_factory()
        shop.show_pet()
        print("=" * 20)
    #print random.choice([1,2,3,4,5])

('This is a lovely', 'Cat')
('It says', 'meow')
('It eats', 'cat food')
====================
('This is a lovely', 'Cat')
('It says', 'meow')
('It eats', 'cat food')
====================
('This is a lovely', 'Dog')
('It says', 'woof')
('It eats', 'dog food')
====================