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A simple decorator to cache the results of function calls
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cache_em_all
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README.md

A simple decorator to cache the results of function calls.

Installation

pip install cache_em_all

Example

from cache_em_all import Cachable

@Cachable("answer.json")
def answer_to(question):
    if question == "life":
        import time
        time.sleep(236500000000000)
        return 42

answer_to("life") # Takes 7.5 million years
answer_to("life") # Pretty much instant

After the first call to answer_to, the result of the function is stored in a file cache/answer/answer__life.json. When the function is called again (with the same parameters), instead of executing the function, the decorator will get the result from the file.

Advanced usage

File types

Various file types are supported.

extension Description
csv Uses pandas to save the result in a csv file. The return value for the function must be a DataFrame or Series.
json Saves the result in a json file. Useful for lists, dictionaries and primitive types.
pkl Pickles the return value. Return type can be just about anything. May not work well for large (>~2GB) files
pa Uses pyarrow to save files. This is generally faster than pkl and supports larger files (tested up to 50GB)

Versioning

The Cachable decorator can accept a version number. This is useful for when you update a function. For example,

You had the following code:

from cache_em_all import Cachable

@Cachable("add.json")
def add(x, y):
    return x + x

This is a bug (should be x+y, not x+x), but you've run this function multiple times and there are lots of cached results. Rather than manually deleting the cache folder, you can bump the version number (version numbers start at 0).

from cache_em_all import Cachable

@Cachable("add.json", version=1)
def add(x, y):
    return x + y

Now next time the function is called it will invalidate the cache and re-run the function.

Do not use this feature in multi-processing code because the writes to the version file do not (yet) use locks.

Folder

By default all cached files are stored in a folder called cache. This can be changed for each function by passing folder to Cachable.

from cache_em_all import Cachable

@Cachable("add.json", folder="/mnt/ram/fastcache")
def add(x, y):
    return x + y

You can also change the default cache dir so that all cache files are by default saved elsewhere.

from cache_em_all import Cachable, set_cache_dir
set_cache_dir("/mnt/huge_hdd")

@Cachable("add.json")
def add(x, y):
    return x + y

Disable cache

You can also disable the cache by setting use to False.

from cache_em_all import Cachable

@Cachable("add.json", use=False)
def add(x, y):
    return x + y

This can be useful for debugging or optmizing the function.

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