[Python-Dev] A grammatical oddity: trailing commas in argument lists. (original) (raw)

Mark Dickinson dickinsm at gmail.com
Fri Jul 9 16:40:13 CEST 2010

While looking at a parser module issue (http://bugs.python.org/issue9154) I noticed that Python's grammar doesn't permit trailing commas after keyword-only args. That is,

def f(a, b,):  pass

is valid syntax, while

def f(*, a, b,): pass

is not. I was just curious whether the latter was deliberate or an oversight. And if an oversight, is it worth fixing after the moratorium expires? (See also http://bugs.python.org/issue2009.)

Mark

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