On Mon, Jun 19, 2023 at 12:42 PM Chris Angelico via Python-list < python-list@python.org> wrote:
> On Tue, 20 Jun 2023 at 02:37, Peter Bona via Python-list > <python-list@python.org> wrote: > > > > Hi > > > > I am wondering if there has been any discussion why NoneType is not > iterable My feeling is that it should be. > > Sometimes I am using API calls which return None. > > If there is a return value (which is iterable) I am using a for loop to > iterate. > > > > Now I am getting 'TypeError: 'NoneType' object is not iterable'. > > > > (Examples are taken from here > https://rollbar.com/blog/python-typeerror-nonetype-object-is-not-iterable/ > ) > > Example 1: > > mylist = None > > for x in mylist: > > print(x) <== will raise TypeError: 'NoneType' object is not iterable > > Solution: extra If statement > > if mylist is not None: > > for x in mylist: > > print(x) > > > > > > I think Python should handle this case gracefully: if a code would > iterate over None: it should not run any step. but proceed the next > statement. > > > > Has this been discussed or proposed? > > > > Try this instead: > > for x in mylist or (): > > Now a None list will skip iteration entirely, allowing you to get the > effect you want :) > > ChrisA > -- > https://mail.python.org/mailman/listinfo/python-list > I prefer iteration of None to be an error, as in my usage it usually indicates a mistake that I'd want to catch -- https://mail.python.org/mailman/listinfo/python-list
