On 12/06/2023 21:11, Barry wrote:
On 12 Jun 2023, at 16:55, BoppreH via Python-ideas <python-ideas@python.org> wrote:
Then the empty list creates hard-to-track bugs. I'm familiar with the iterator protocol and why the behavior above happens, but couldn't it be prevented? I don’t think so. It is not always a bug that an iterator is empty. For example this pattern:
args = iter(sys.argv) progname = next(args) mandatory_arg = next(args) for arg in args: print(‘optional arg’, next(arg))
Your proposal will traceback for the for loop if there are no optional args.
Barry
I don't think so. Using the OP's implementation, the is_exhausted flag has not been set when the for-loop is entered. It is of course set after the for-loop has been exited, so a subsequent attempt to iterate over "args" will raise the Exception. (The OP's post confirming this arrived while I was typing this e-mail. 😁) Also the OP's request was for generators, not for any iterator. Nonetheless, I do not support the proposal, for backward compatibility reasons. I *can* imagine sane code that relies on the existing behaviour. Best wishes Rob Cliffe