On 2 March 2017 at 14:24, Steven D'Aprano <st...@pearwood.info> wrote: > I like this! If the caller doesn't provide a value, the parameter > remains unbound and any attempt to look it up will give a NameError or > UnboundLocalError.
Hmm. But those exceptions currently indicate with almost 100% certainty, a programming error (usually a mis-spelled name or a control flow error). The proposal makes them a normal runtime behaviour, in certain circumstances. What would happen if you mis-spelled the name of the optional parameter? You'd get a NameError from using the wrong name, rather than from the user not supplying a value. I don't think re-using NameError is a good idea here. Paul _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
