cachegrab

cachegrab is a Python package that provides decorators for caching instance methods.

Installation

pip install cachegrab

Main Features

• deep_cached_property ➔ Inspired by functools.cached_property, this decorator provides a deep copy of cached return values, ensuring they remain immutable after their initial access. The original return values are preserved in a dictionary named self._deep_cache.
• cached_attribute ➔ this decorator returns an internal attribute with the same name as the original, prefixed with an underscore.

Example Usage

Imports

from cachegrab import deep_cached_property, cached_attribute
from functools import cached_property

Decorate Instance Methods

Consider the example class Dog below:

• toys ➔ decorated with cached_property because toys can be buried and are therefore mutable.
• is_good_boy ➔ decorated with deep_cached_property because his good boy status is never in question.
• tricks ➔ decorated with cached_attribute to prevent direct overwrites.

class Dog(object):

    @cached_property
    def toys(self):
        return {'ball','bone'}

    @deep_cached_property
    def is_good_boy(self):
        return True

    @cached_attribute
    def tricks(self):
        return {'sit','shake'}

    def bury_toys(self):
        while self.toys:
            self.toys.pop()

We will attempt to modify both cached properties:

dog = Dog()
dog.bury_toys()
dog.good_boy = False

Let's look at the results:

print('dog toys ➜', ', '.join(dog.toys) if dog.toys else '?')
print('good boy? ➜', dog.is_good_boy)
print('_deep_cache ➜', dog._deep_cache)

dog.tricks # access tricks property
print('_tricks ➜', dog._tricks)

dog toys ➜ ?
good boy? ➜ True
_deep_cache ➜ {'is_good_boy': True}
_tricks ➜ {'sit','shake'}