app-json-file-cache 0.2.2

Description:

appjsonfilecache 0.2.2

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 is human-readable.
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.


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.