presistent_cache.py

import shelve
from functools import wraps

def persistent_cache(cache_file='.cache'):
    """Using shelve module creates a cache that persists across executions.
    Depends on repr giving a univocal representation of input arguments.
    """
    def decorator(func):
        @wraps(func)
        def wrapper(*args, **kwargs):
            with shelve.open(cache_file) as db:
                key = f'{func.__module__}.{func.__qualname__}(*{repr(args)}, **{repr(kwargs)})'
                try:
                    return db[key]
                except KeyError:
                    result = func(*args, **kwargs)
                    db[key] = result
                    return result
        return wrapper
    return decorator