factory_method.py

'''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 str(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, j = get_localizer("English"), get_localizer("Greek")  
# Localize some text 
for msgid in "dog parrot cat bear".split():     
    print(e.get(msgid), j.get(msgid))