get.py

# -*- coding:utf-8 -*-
from datetime import datetime


class Get(object):               
    """
    Lazy value calculate for object
    """
    def __init__(self, getter):
        self.getter = getter

    def __get__(self, instance, type):
        return self.getter()


class ObjectDict(dict): 
    """
    Object like dict, every dict[key] can visite by dict.key
    
    If dict[key] is `Get`, calculate it's value. 

    """
    def __getattr__(self, name):
        """
        if Object has attr name, Object.name will call it, else will call Object.__getattr__ function
        """
        ret = self.__getitem__(name)
        if hasattr(ret, '__get__'):
            return ret.__get__(self, ObjectDict)
        return ret


od = ObjectDict(now=Get(datetime.now))
print(od.now)
print(od.now)
# 2014-12-10 21:29:14.072379
# 2014-12-10 21:29:14.072392