Ravenport: python-cached-property

Subpackage Descriptions

single

# cached-property [Github Actions status] [PyPI] [![Code style: ruff]](https://github.com/astral-sh/ruff) A decorator for caching properties in classes. ## Why? * Makes caching of time or computational expensive properties quick and easy. * Because I got tired of copy/pasting this code from non-web project to non-web project. * I needed something really simple that worked in Python 2 and 3. (Python 3.8 added a version of this decorator as [`@functools.cached_property`].) ## How to use it Let's define a class with an expensive property. Every time you stay there the price goes up by $50! ```python class Monopoly: def __init__(self): self.boardwalk_price = 500 @property def boardwalk(self): # In reality, this might represent a database call or time # intensive task like calling a third-party API. self.boardwalk_price += 50 return self.boardwalk_price ``` Now run it: ```python >>> monopoly = Monopoly() >>> monopoly.boardwalk 550 >>> monopoly.boardwalk 600 ``` Let's convert the boardwalk property into a `cached_property`. ```python from cached_property import cached_property class Monopoly(object): def __init__(self): self.boardwalk_price = 500 @cached_property def boardwalk(self): # Again, this is a silly example. Don't worry about it, this is # just an example for clarity. self.boardwalk_price += 50 return self.boardwalk_price ``` Now when we run it the price stays at $550. ```python >>> monopoly = Monopoly() >>> monopoly.boardwalk 550 >>> monopoly.boardwalk 550 >>> monopoly.boardwalk 550 ``` Why doesn't the value of `monopoly.boardwalk` change? Because it's a **cached property**! ## Invalidating the Cache Results of cached functions can be invalidated by outside forces. Let's demonstrate how to force the cache to invalidate: ```python >>> monopoly = Monopoly() >>> monopoly.boardwalk 550 >>> monopoly.boardwalk 550 >>> # invalidate the cache >>> del monopoly.__dict__['boardwalk'] >>> # request the boardwalk property again >>> monopoly.boardwalk 600 >>> monopoly.boardwalk 600 ```

Port variant	v13
Summary	Decorator for caching properties in classes (3.13)
BROKEN
Package version	2.0.1
Homepage	https://github.com/pydanny/cached-property
Keywords	python
Maintainer	Python Automaton
License	Not yet specified
Other variants	v12
Ravenports	Buildsheet \| History
Ravensource	Port Directory \| History
Last modified	15 NOV 2024, 16:08:50 UTC
Port created	10 MAR 2020, 23:46:28 UTC

Build (only)	python313:dev:std python-pip:single:v13 autoselect-python:single:std
Build and Runtime	python313:primary:std