Note: This question (and the original part of my answer to it) are only really meaningful for Python versions prior to 3.7. The behavior that was asked about no longer happens in 3.7 and later, thanks to changes described in PEP 479. So this question and the original answer are only really useful as historical … Read more
There’s no need to explicitly raise StopIteration as that’s what a bare return statement does for a generator function – so yes they’re the same. But no, just using return is more Pythonic. From: http://docs.python.org/2/reference/simple_stmts.html#the-return-statement (valid to Python 3.2) In a generator function, the return statement is not allowed to include an expression_list. In that … Read more
If you are using Python 2.6+ you should use the next built-in function, not the next method (which was replaced with __next__ in 3.x). The next built-in takes an optional default argument to return if the iterator is exhausted, instead of raising StopIteration: next((i for i, v in enumerate(a) if i == 666), None)
To judge from the file paths, it looks like you’re running Python 3.7. If so, you’re getting caught by new-in-3.7 behavior: PEP 479 is enabled for all code in Python 3.7, meaning that StopIteration exceptions raised directly or indirectly in coroutines and generators are transformed into RuntimeError exceptions. (Contributed by Yury Selivanov in bpo-32670.) Before … Read more
The for loop listens for StopIteration explicitly. The purpose of the for statement is to loop over the sequence provided by an iterator and the exception is used to signal that the iterator is now done; for doesn’t catch other exceptions raised by the object being iterated over, just that one. That’s because StopIteration is … Read more