memoize to disk - python - persistent memoization

Question

Is there a way to memoize the output of a function to disk?

I have a function

def getHtmlOfUrl(url):
    ... # expensive computation

<

Answer 1

A cleaner solution powered by Python's Shelve module. The advantage is the cache gets updated in real time via well-known dict syntax, also it's exception proof(no need to handle annoying KeyError).

import shelve
def shelve_it(file_name):
    d = shelve.open(file_name)

    def decorator(func):
        def new_func(param):
            if param not in d:
                d[param] = func(param)
            return d[param]

        return new_func

    return decorator

@shelve_it('cache.shelve')
def expensive_funcion(param):
    pass

This will facilitate the function to be computed just once. Next subsequent calls will return the stored result.