Demo of a property on a class

property_example.py

class Foo(object):

    def __init__(self):
        self.datasource = something
        self.cache = {}

    @property
    def data(self):
        if 'data' in cache.keys():
            return cache['data']
        else:
            cache['data'] = get_data(self.datasource)
            return cache['data']

    @data.setter
    def data(self, new_data):
        # Update the cache
        cache['data'] = new_data

f = Foo()
f.data  # returns the data