Python Exceptions: EAFP and What is Really Exceptional?

Question

It\'s been said in a couple places (here and here) that Python\'s emphasis on \"it\'s easier to ask for forgiveness than permission\" (EAFP) should be tempered with the idea

Answer 1

Just for the record, i'd write is like this:

import heapq
a_list = range(20)
pq = a_list[:]
heapq.heapify(pq)
try:
    while True:
        min1 = heapq.heappop(pq)
        min2 = heapq.heappop(pq)
        heapq.heappush(pq, min1 + min2)
except IndexError:
    pass # we ran out of numbers in pq

Exceptions can leave a loop (even functions) and you can use them for that. Since Python throws them everywhere, I think this pattern is quite useful (even pythonic).