40. Saving objects to file

In the example below, although pickle is a great way to save objects, shelve is an alternative to saving multiple data/objects into a central location.

40.1. Don’t do this

import pickle

object_1 = 'pretend some big object 1'
object_2 = 'pretend some big object 2'
data = {
    'object_1': object_1,
    'object_2': object_2,
}

# write to file
pickle.dump(data, open('data.p', 'wb'))

# read from file
data = pickle.load(open('data.p', 'rb'))

40.2. Do this

import shelve

object_1 = 'pretend some big object 1'
object_2 = 'pretend some big object 2'

# write to file
with shelve.open('data') as s:
    s['object_1'] = object_1
    s['object_2'] = object_2

# read from file
with shelve.open('data') as s:
    print(s['object_1'])
    print(s['object_2'])