factory_method.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

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


class GreekGetter:

 """A simple localizer a la gettext"""

 def __init__(self):
 self.trans = dict(dog="σκύλος", cat="γάτα")

 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 get(self, msgid):
 return str(msgid)


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

# Create our localizers
e, g = get_localizer(language="English"), get_localizer(language="Greek")
# Localize some text
for msgid in "dog parrot cat bear".split():
 print(e.get(msgid), g.get(msgid))

### OUTPUT ###
# dog σκύλος
# parrot parrot
# cat γάτα
# bear bear