Cache the result of any function

cache.py

# -- the cache snippet ---------------------------------------------------------

from os import makedirs
from os.path import exists, dirname
from pickle import load as pload, dump as pdump
from re import sub
from time import time

def cache(target, args, identifier=None, cache_life=3 * 24 * 3600):
	""" Run the target function with the given args, and store it to a pickled
	cache folder using the given identifier or the name of the function. It will
	be stored for cache_life seconds. """
	if identifier == None:
		identifier = target.__name__
	path = ".pickled/%s.pk" % sub(r"[/\\\*;\[\]\":=,<>]", "_", identifier)
	makedirs(dirname(path), exist_ok=True)
	now = time()
	if exists(path):
		with open(path, "rb") as fp:
			save_time, value = pload(fp)
		if now - save_time <= cache_life:
			return value
	res = target(*args)
	with open(path, "wb") as fp:
		pdump((now, res), fp, protocol=3)
	return res

# -- the usage example ---------------------------------------------------------

def fact_mod(n, mod):
	""" Dummy function to give an example of use. Computes n! % mod. """
	res = n
	while n > 1:
		n -= 1
		res *= n
	return res % mod

if __name__ == "__main__":
	n = 100000
	mod = 104729
	name = "fact_%s_mod_%s" % (n, mod)
	value = cache(fact_mod, (n, mod), identifier=name)
	print(value)