Lazy loading of class attributes

Class Foo has a bar, and it is not loaded until it is accessed. Further accesses to bar should incur no overhead.

class Foo(object):

    def get_bar(self):
        print "initializing"
        self.bar = "12345"
        self.get_bar = self._get_bar
        return self.bar

    def _get_bar(self):
        print "accessing"
        return self.bar

Is it possible to do something like this using properties or, better yet, attributes, instead of using a getter method?

The goal is to lazy load without overhead on all subsequent accesses...