custom dict that allows delete during iteration

Question

UPDATED based on Lennart Regebro\'s answer

Suppose you iterate through a dictionary, and sometimes need to delete an element. The following is very efficient:

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Answer 1

You can accomplish this by iterating over a static list of the key/value pairs of the dictionary, instead of iterating over a dictionary view.

Basically, iterating over list(dict_.items()) instead of dict_.items() will work:

for k, v in list(dict_.items()):
  if condition(k, v):
    del dict_[k]
    continue
  # do other things you need to do in this loop

Here is an example (ideone):

dict_ = {0: 'a', 1: 'b', 2: 'c', 3: 'd', 4: 'e', 5: 'f', 6: 'g'}
for k, v in list(dict_.items()):
    if k % 2 == 0:
        print("Deleting  ", (k, v))
        del dict_[k]
        continue
    print("Processing", (k, v))

and the output:

Deleting   (0, 'a')
Processing (1, 'b')
Deleting   (2, 'c')
Processing (3, 'd')
Deleting   (4, 'e')
Processing (5, 'f')
Deleting   (6, 'g')