On 26 November 2017 at 09:22, Terry Reedy <tjre...@udel.edu> wrote: > Since return and yield are often the first half of a cross-namespace > assignment, requiring the () is a bit surprising. Perhaps someone else has > a good reason for the difference.
These kinds of discrepancies tend to arise because there are a few different grammar nodes for "comma separated sequence of expressions", which makes it possible to miss some when enhancing the tuple syntax. Refactoring the grammar to eliminate the duplication isn't especially easy, and we don't change the syntax all that often, so it makes sense to treat cases like this one as bugs in the implementation of the original syntax change (except that the "don't change the Grammar in maintenance releases" guideline means they still need to be handled as new features when it comes to fixing them). Cheers, Nick. P.S. That said, I do wonder if it might be feasible to write a "Grammar consistency check" test that ensured the known duplicate nodes at least have consistent definitions, such that missing one in a syntax update will cause an automated test failure. Unfortunately, the nodes typically haven't been combined because they have some *intentional* differences in exactly what they allow, so I also suspect that this is easier said than done. -- Nick Coghlan | ncogh...@gmail.com | Brisbane, Australia _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
