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

User · Answer

You can use my simple solution to the problem. It is really straightforward, nothing fancy:

class MemCache(dict):
    def __init__(self, fn):
        dict.__init__(self)
        self.__fn = fn

    def __getitem__(self, item):
        if item not in self:
            dict.__setitem__(self, item, self.__fn(item))
        return dict.__getitem__(self, item)

mc = MemCache(lambda x: x*x)

for x in xrange(10):
    print mc[x]

for x in xrange(10):
    print mc[x]

It indeed lacks expiration funcionality, but you can easily extend it with specifying a particular rule in MemCache c-tor.

Hope code is enough self-explanatory, but if not, just to mention, that cache is being passed a translation function as one of its c-tor params. It's used in turn to generate cached output regarding the input.

Hope it helps

User · Answer

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

User · Answer

Take a look at Beaker    Home Page Caching Documentation Good quick-start article about using Beaker with Django  but useful in any other apps too

User · Answer

No one has mentioned shelve yet  https   docs python org 2 library shelve html  It isn t memcached  but looks much simpler and might fit your need

User · Answer

From Python 3 2 you can use the decorator  lru cache from the functools library  It s a Last Recently Used cache  so there is no expiration time for the items in it  but as a fast hack it s very useful   from functools import lru cache   lru cache maxsize 256  def f x     return x x  for x in range 20     print f x  for x in range 20     print f x

User · Answer

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   lt CachedItem   s  s  expires at   s gt      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  lt  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

User · Answer

ExpiringDict is another  option  https   pypi org project expiringdict

User · Answer

Joblib https   joblib readthedocs io supports caching functions in the Memoize pattern  Mostly  the idea is to cache computationally expensive functions    gt  gt  gt  from joblib import Memory  gt  gt  gt  mem   Memory cachedir   tmp joblib    gt  gt  gt  import numpy as np  gt  gt  gt  square   mem cache np square   gt  gt  gt    gt  gt  gt  a   np vander np arange 3   astype np float   gt  gt  gt  b   square a                                                                                                                       Memory  Calling square    square array    0    0    1             1    1    1             4    2    1                                                                 square - 0   s  0 0min   gt  gt  gt  c   square a    You can also do fancy things like using the  memory cache decorator on functions  The documentation is here  https   joblib readthedocs io en latest generated joblib Memory html

User · Answer

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

User · Answer

This project aims to provide  quot Caching for humans quot   seems like it s fairly unknown though  Some info from the project page  Installation pip install cache Usage  import pylibmc from cache import Cache  backend   pylibmc Client   quot 127 0 0 1 quot     cache   Cache backend    cache  quot mykey quot   def some expensive method        sleep 10      return 42    writes 42 to the cache some expensive method      reads 42 from the cache some expensive method      re-calculates and writes 42 to the cache some expensive method refresh      get the cached value or throw an error    unless default  was passed to  cache       some expensive method cached

User · Answer

keyring is the best python caching library  You can use  keyring set password  service   jsonkey  json res   json res  keyring get password  service   jsonkey    json res  keyring core delete password  service   jsonkey

User · Answer

Try redis  it is one of the cleanest and easiest solutions for applications to share data in a atomic way or if you have got some web server platform  Its very easy to setup  you will need a python redis client http   pypi python org pypi redis

User · Answer

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

User · Answer

Look at gocept cache on pypi  manage timeout

[python] Is there a Python caching library?

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