Python lazy attribute property

lazy_property.py

class lazy_property(object):
    '''
    This decorator is meant to be used for lazy evaluation of an object attribute.
    The property should represent non-mutable data, as it replaces itself.
    
    Example:
    
    class Configuration(object):        
    
        def __init__(self):        
            config = ConfigParser.ConfigParser()
            self._config= config.read('/etc/mytool/site.cfg')
            
        @lazy_property
        def verbosity(self):
            return self._config.get("common", "verbosity")
        
        @lazy_property
        def foobar_url(self):
            return self._config.get("foobar", "url")
    '''

    def __init__(self,fget):
        self.fget = fget
        self.func_name = fget.__name__


    def __get__(self,obj,cls):
        if obj is None:
            return None
        value = self.fget(obj)
        setattr(obj,self.func_name,value)
        return value