Caching decorator with timeout. Might not be good for class instance/class methods.

cache_decorator.py

from functools import wraps
from json import dumps
from datetime import datetime


def timeout_cache(max_timeout):
    def timeout_cache_inner(fn):
        fn._cache = {}
        fn._timeout = max_timeout
        @wraps(fn)
        def cached(*args, **kwargs):
            key = "%s - %s" % (
                dumps(args), dumps(kwargs))
            cache, timeout = fn._cache, fn._timeout
            now = datetime.now()
            if key not in cache or
                    now - cache[key]["time"] > timeout:
                value = fn(*args, **kwargs)
                cache[key] = {
                    "time": now,
                    "value": value
                }
            return cache[key]["value"]
        return cached
    return timeout_cache_inner