[issue2009] Grammar change to prevent shift/reduce problem with varargslist
Mark Dickinson
report at bugs.python.org
Fri Jul 9 11:28:07 CEST 2010
Mark Dickinson <dickinsm at gmail.com> added the comment:
+!. I had to do a very similar refactoring recently when trying to fix the parser module to understand keyword-only arguments and annotations.
Taking keyword-only arguments into account, I think the replacement needs to be:
varargslist: (vfpdef ['=' test] (',' vfpdef ['=' test])* [','
['*' [vfpdef] (',' vfpdef ['=' test])* [',' '**' vfpdef] | '**' vfpdef]]
| '*' [vfpdef] (',' vfpdef ['=' test])* [',' '**' vfpdef] | '**' vfpdef)
and the analogous replacement needs to be made in the production for 'typedargslist', too.
BTW, I'm a bit surprised that the grammar doesn't allow for trailing commas after keyword-only arguments: that is,
def f(a, b,): ... is fine, but
def f(*, a, b,): ... is a SyntaxError
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nosy: +mark.dickinson
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