Expert Python Programming - Second Edition

Other syntax elements you may not know yet

There are some elements of the Python syntax that are not popular and rarely used. It is because they either provide very little gain or their usage is simply hard to memorize. Due to this, many Python programmers (even with years of experience) simply do not know about their existence. The most notable examples of such features are as follows:

• The for … else clause
• Function annotations

The for … else … statement

Using the else clause after the for loop allows you to execute a code of block only if the loop ended "naturally" without terminating with the break statement:

>>> for number in range(1):
...     break
... else:
...     print("no break")
...
>>>
>>> for number in range(1):
...     pass
... else:
... print("break") ...