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.
• protected_attribute ➔ Decorator that returns the protected attribute corresponding to the name of the decorated function. If the protected attribute does not exist, it sets the attribute to the return value of the decorated function.

Example Usage

Imports

from cachegrab import deep_cached_property, protected_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 protected_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

    @protected_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'}