memoria 2021.6.30.1

Python library of hashing and caching

Memoria

Memoria is a Python library for hashing and caching.

Installation

pip install memoria

Benefits of Memoria

Consistency

Unfortunately the built-in hash method is not consistent. For example if you hash a string in two different Python sessions, e.g., hash('hello world!'), you may get different results, e.g., -69600567246316219 or -8701498716516122875. However, Memoria is consistent, e.g., memoria.hash('hello world!') produces PwDVM4wattDXKR1HUtszcPP5BHTUVTYQ5X0cO51yAn4=. We should credit the built-in library hashlib of course.

Hashing Unhashable Types

Memoria can hash virtually anything. If you use the built-in hash method hash(dict()) or hash(list()) you will get an error: TypeError: unhashable type: 'dict' but Memoria can even hash unhashable types by converting them into a hashable type and hashing the result. To make sure that the hash is still different between the original type and the hashable representation, Memoria takes some additional measures.

Usage

import memoria

# hashing a python object
memoria.hash(123)
# >>> 'zi+wk24s9wwA/UiNRKbjeu6JfDi78yCj7yVL87sS0Ko='

# base is 64 by default but 32 can also be used. 
# base 64 should not be used in the file-system, e.g., file names, because it has inadmissible characters.
memoria.hash(123, base=32)
# >>> 'PONR14RE5JRGO07T926K99N3FBN8IV1ONFPI18VF4L5V7EOIQ2L0----'

# dictionaries are unhashable but Memoria can hash them
memoria.hash({'name': 'John', 'age': 24})
# >>> 'ioCMz5B8pcdk2CxcbIX/3n3qnQRn/yv9/zvC5Wc0YlU='