app\_json\_file\_cache
======================
Provides a function decorator that caches the return value in a JSON file in the appropriate application cache directory.
It requires all function parameters and return values to be encodeable to JSON, so that the cache content
is human-readable. The file names are based on a SHA512 hash of the function parameters.
It supports a "vary" guard value (e.g. a data model version) that protects against using old versions of cache.
Additionally, a cheaper default function (e.g. returning shipped, precalculated values) can be specified as a stand-in
until an explicit recalculate function is called.
.. image:: https://img.shields.io/pypi/v/app-json-file-cache
:alt: PyPI
:target: https://pypi.org/project/app-json-file-cache/
.. image:: https://github.com/JohannesEbke/app_json_file_cache/actions/workflows/test.yaml/badge.svg
:target: https://github.com/JohannesEbke/app_json_file_cache/actions/workflows/test.yaml/
Usage
-----
Example usage::
from app_json_file_cache import AppCache
cache = AppCache("myapp")
@cache("expensive")
def expensive_function():
return calculator()
More Example usage::
from app_json_file_cache import AppCache
cache = AppCache("myapp")
@cache("expensive", vary=VERSION)
def expensive_function(param):
return calculator(param)
expensive_function.recalculate(param1) # recalculate if external effects change
Using a default function until the next recalculate::
from app_json_file_cache import AppCache
cache = AppCache("myapp")
def cheap_standin(param):
return estimate(param)
@cache("expensive", vary=VERSION, cheap_default_func=cheap_standin)
def expensive_function(param):
return calculator(param)
expensive_function(param1) # cheap_standin is used
expensive_function.recalculate(param1) # cache is updated with expensive_function
expensive_function(param1) # cached value from expensive_function is used
Caveats
-------
* Names must be unique per app. If you reuse names, chaos ensues.
* Each set of function parameter values creates a new file. This may lead to too many files in a directory on some systems.
* Mixing positional and keyword arguments is not supported
* It's your responsibility that return values are serializable to JSON.
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"description": "app\\_json\\_file\\_cache\n======================\n\nProvides a function decorator that caches the return value in a JSON file in the appropriate application cache directory.\n\nIt requires all function parameters and return values to be encodeable to JSON, so that the cache content\nis human-readable. The file names are based on a SHA512 hash of the function parameters.\n\nIt supports a \"vary\" guard value (e.g. a data model version) that protects against using old versions of cache.\n\nAdditionally, a cheaper default function (e.g. returning shipped, precalculated values) can be specified as a stand-in\nuntil an explicit recalculate function is called.\n\n.. image:: https://img.shields.io/pypi/v/app-json-file-cache\n :alt: PyPI\n :target: https://pypi.org/project/app-json-file-cache/\n\n.. image:: https://github.com/JohannesEbke/app_json_file_cache/actions/workflows/test.yaml/badge.svg\n :target: https://github.com/JohannesEbke/app_json_file_cache/actions/workflows/test.yaml/\n\n\nUsage\n-----\n\nExample usage::\n\n from app_json_file_cache import AppCache\n cache = AppCache(\"myapp\")\n\n @cache(\"expensive\")\n def expensive_function():\n return calculator()\n\nMore Example usage::\n\n from app_json_file_cache import AppCache\n cache = AppCache(\"myapp\")\n\n @cache(\"expensive\", vary=VERSION)\n def expensive_function(param):\n return calculator(param)\n\n expensive_function.recalculate(param1) # recalculate if external effects change\n\nUsing a default function until the next recalculate::\n\n from app_json_file_cache import AppCache\n cache = AppCache(\"myapp\")\n\n def cheap_standin(param):\n return estimate(param)\n\n @cache(\"expensive\", vary=VERSION, cheap_default_func=cheap_standin)\n def expensive_function(param):\n return calculator(param)\n\n expensive_function(param1) # cheap_standin is used\n expensive_function.recalculate(param1) # cache is updated with expensive_function\n expensive_function(param1) # cached value from expensive_function is used\n\nCaveats\n-------\n\n* Names must be unique per app. If you reuse names, chaos ensues.\n* Each set of function parameter values creates a new file. This may lead to too many files in a directory on some systems.\n* Mixing positional and keyword arguments is not supported\n* It's your responsibility that return values are serializable to JSON.\n",
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