New submission from paul rubin <phr-pythonb...@nightsong.com>:
Inspired by a question on comp.lang.python about how to deal with an int set composed of integers and ranges. Range objects like range(1,5,2) contain start, stop, and step values, but it's messy and potentially tricky to get the actual first and last values of the range. Examples: range(1,5,2) - first = 1, last = 3 range (5, 1, 2) - range is empty, first = last = None range(5, 1, -1) - first is 5, last is 2 Note in the case where the range is not empty, you can get the "last" by a messy calculation but it's easier to pick the first element from the reverse iterator. But then you might forget to catch the stopiteration exception in the case that the list is empty. The same goes for the first element, roughly. And constructing the iterators just to pick one element seems like unnecessary overhead. So it is better to have actual methods for these, with type Optional[int]. Then mypy should remind you to check for the empty case if you forget. ---------- messages: 416962 nosy: phr priority: normal severity: normal status: open title: add methods to get first and last elements of a range type: enhancement _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue47257> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
