python - Make @lru_cache ignore some of the function arguments

Question

How can I make @functools.lru_cache decorator ignore some of the function arguments with regard to caching key?

For example, I have a function that looks like this:

def find_object(db_handle, query):
    # (omitted code)
    return result

If I apply lru_cache decorator just like that, db_handle will be included in the cache key. As a result, if I try to call the function with the same query, but different db_handle, it will be executed again, which I'd like to avoid. I want lru_cache to consider query argument only.

question from:https://stackoverflow.com/questions/30730983/make-lru-cache-ignore-some-of-the-function-arguments

Answer 1

With cachetools you can write:

from cachetools import cached
from cachetools.keys import hashkey

from random import randint

@cached(cache={}, key=lambda db_handle, query: hashkey(query))
def find_object(db_handle, query):
    print("processing {0}".format(query))
    return query

queries = list(range(5))
queries.extend(range(5))
for q in queries:
    print("result: {0}".format(find_object(randint(0, 1000), q)))