Python 2.7 - How to delete a dictionary using a function?

Question

I have the following function in Python 2.7.5.6:

"""
Delete entire *existing* store from memory. Prior to doing so, a backup
copy of the store is saved to disk with the current date and time as
part of the filename:
"""
def drop(store):
    backup(store)
    del store
    ## BUGGY: the store is preserved in its entirety

where store is a dictionary. If I issue every command in the body of the above function in a Python Shell (IDLE), I get the desired behavior. However, calling the function drop() doesn't work; the store dictionary is not deleted and is preserved. Any help would be greatly appreciated!

Answer 1

That is because you are simply deleting the local copy of the dictionary store that you passed in as a parameter. If you want to delete the original dictionary, just call the del(store) method in your code where you actually need to delete store as follows:

def drop(store):
    backup(store)

store = {}
drop(store)
del store

Answer 2

You could make store an object which contains a dictionary; this would give you access to delete it from inside your function:

class Store:
    def __init__(self, data=None):
        self.data = data or {}

    def clear(self):
        backup(self.data)
        self.data = {}

store = Store()

def drop(store):
    store.clear()

Answer 3

You could also do

def drop(local_store):
    global store
    backup(local_store)
    del store

store = {}   
drop(store)