Is there a Python caching library?

Question

I'm looking for a Python caching library but can't find anything so far. I need a simple dict-like interface where I can set keys and their expiration and get them back cached. Sort of something like:

cache.get(myfunction, duration=300)

which will give me the item from the cache if it exists or call the function and store it if it doesn't or has expired. Does anyone know something like this?

Answer 1

Take a look at Beaker:

• Home Page
• Caching Documentation

Answer 2

I think the python memcached API is the prevalent tool, but I haven't used it myself and am not sure whether it supports the features you need.

Answer 3

import time

class CachedItem(object):
    def __init__(self, key, value, duration=60):
        self.key = key
        self.value = value
        self.duration = duration
        self.timeStamp = time.time()

    def __repr__(self):
        return '<CachedItem {%s:%s} expires at: %s>' % (self.key, self.value, time.time() + self.duration)

class CachedDict(dict):

    def get(self, key, fn, duration):
        if key not in self \
            or self[key].timeStamp + self[key].duration < time.time():
                print 'adding new value'
                o = fn(key)
                self[key] = CachedItem(key, o, duration)
        else:
            print 'loading from cache'

        return self[key].value



if __name__ == '__main__':

    fn = lambda key: 'value of %s  is None' % key

    ci = CachedItem('a', 12)
    print ci 
    cd = CachedDict()
    print cd.get('a', fn, 5)
    time.sleep(2)
    print cd.get('a', fn, 6)
    print cd.get('b', fn, 6)
    time.sleep(2)
    print cd.get('a', fn, 7)
    print cd.get('b', fn, 7)

Answer 4

You might also take a look at the Memoize decorator. You could probably get it to do what you want without too much modification.

Answer 5

Look at gocept.cache

Answer 6

Look at bda.cache http://pypi.python.org/pypi/bda.cache - uses ZCA and is tested with zope and bfg.