On Sun, Oct 16, 2016 at 12:10 PM, Steven D'Aprano <st...@pearwood.info> wrote: > On Sun, Oct 16, 2016 at 04:36:05AM +1100, Chris Angelico wrote: >> On Sun, Oct 16, 2016 at 4:33 AM, אלעזר <elaz...@gmail.com> wrote: >> > You are confusing here two distinct roles of the parenthesis: >> > disambiguation >> > as in "(1 + 2) * 2", and tuple construction as in (1, 2, 3). This overload >> > is the reason that (1) is not a 1-tuple and we must write (1,). >> >> Parentheses do not a tuple make. Commas do. >> >> 1, 2, 3, # three-element tuple >> 1, 2, # two-element tuple >> 1, # one-element tuple >> >> The only time that a tuple requires parens is when it's the empty tuple, (). > > Or to disambiguate a tuple from some other comma-separated syntax. Hence > why you need the parens here: > > [(b, a) for a,b in sequence]
Yes, in the same way that other operators can need to be disambiguated. You need to say (1).bit_length() because otherwise "1." will be misparsed. You need parens to say x = (yield 5) + 2, else it'd yield 7. But that's not because a tuple fundamentally needs parentheses. ChrisA _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
