Python snippet: for…else

Python has a clever for...else (albeit ancient by now) construct allowing the use of an else suite. Consider the following example, written without the for…else construct:

contains_even = False
for element in [1, 2, 3, 4, 5]:
    if element % 2 == 0:
        contains_even = True
        break
if contains_even:
    print "List contains an even element."
else:
    print "List does not contain an even element."

Compare that to the for…else equivalent code, allowing us to remove an additional flag variable:

for element in [1, 2, 3, 4, 5]:
    if element % 2 == 0:
        print "List contains an even element."
        break
else:
    print "List does not contain an even element."

The else suite will be executed unless the preceding loop has been terminated by a break statement. A continue statement will skip the rest of the suite and proceed with the next item, or with the else clause if there was no items remaining.