cached_property.py

from functools import update_wrapper


def cached_property(f, name=None):
    if not name:
        name = f.__name__

    prop = '_%s' % name

    def _get_property(self):
        try:
            value = getattr(self, prop)
        except AttributeError:
            value = f(self)
            setattr(self, prop, value)

        return value

    update_wrapper(_get_property, f)

    def _del_property(self):
        delattr(self, prop)

    return property(_get_property, None, _del_property)

Use thusly:

class F(object):

    @cached_property
    def disinflate(self):
        return some_expensive_method()