Build your own cache in Python

Posted by Jonas Sandström on Wed 11 May 2022

Caching or memoization is the act of storing calculated results in order to avoid having to calculate them again. In Python we have the @cache decorator in the functools module. But I figured it would be fun to write my own. I know it's silly but its also fun to see how a simple implementation of a cache actually works... Its basically just a dictionary with the function name plus its parameters as the key looking up the calculated value.


cache = {}

def my_cache(func):
    def wrapper(*args, **kwargs):
        key = f'{func.__name__}-{args}-{kwargs}'
        if key in cache:
            return cache[key]
        result = func(*args, **kwargs)
        cache[key] = result
        return result
    return wrapper

# How to use it
def try_my_cache(*args, **kwargs):
    return 'This result will just have to wait 3 seconds once.'