Subversion Repositories SmartDukaan

'''

Created on 30-Aug-2011

@author: rajveer

'''

import time

class memoized(object):

    '''

    Simple caching for function returns. 

    Any function return can be memoized for a given time duration.

    Time to live also need to be mentioned. It is represented as number of seconds

    '''

    def __init__(self, ttl):

        self.cache = {}

        self.ttl = ttl

    def __call__(self, func):

        def wrapped_function(*args):

            try:

                now = time.time()

                value, last_update = self.cache[args]

                print "HIT"

                if now - last_update > self.ttl:

                    print "EXPIRED"

                    raise AttributeError

            except (KeyError, AttributeError):

                print "MISS"

                value = func(*args)

                self.cache[args] = value, now

            except TypeError:

                print "MISS"

                return func(*args)

            return value

        return wrapped_function

    def __repr__(self):

        return self.func.__doc__

'''

Example usage

'''

@memoized(0)

def fibonacci(n):

    if n <= 1:

        return n

    return fibonacci(n-2) + fibonacci(n-1)

def main():

    print fibonacci(10)

    print fibonacci(12)

if __name__ == '__main__':

    main()