How to store the result of an executed function and re-use later?

Question

E.g., I have:

def readDb():
    # Fetch a lot of data from db, spends a lot time
    ...
    return aList

def calculation():
    x = readdb()
    # Process          


        

Answer 1

Write a simple decorator:

class memo(object):
    def __init__(self, fun):
        self.fun = fun
        self.res = None
    def __call__(self):
        if self.res is None:
            self.res = self.fun()
        return self.res

@memo
def readDb():
    # ... etc
    return aList

For more general solutions, look here: http://code.activestate.com/recipes/498245-lru-and-lfu-cache-decorators/.