[ python-Bugs-1531016 ] Comma not allowed at the end of argument list for **argument

[SourceForge.net]

Bugs item #1531016, was opened at 2006-07-29 20:21
Message generated for change (Comment added) made by sean_gillespie
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1531016&group_id=5470

Please note that this message will contain a full copy of the comment thread,
including the initial issue submission, for this request,
not just the latest update.
Category: Parser/Compiler
Group: Python 2.4
Status: Open
Resolution: None
Priority: 2
Private: No
Submitted By: Roman Suzi (rnd0110)
Assigned to: Nobody/Anonymous (nobody)
Summary: Comma not allowed at the end of argument list for **argument

Initial Comment:
This tells it all:

>>> str('sdfd', **a,)
  File "<stdin>", line 1
    str('sdfd', **a,)
                   ^
SyntaxError: invalid syntax

>>> str('sdfd', *a,)
  File "<stdin>", line 1
    str('sdfd', *a,)
                   ^
SyntaxError: invalid syntax

While the docs tell otherwise:

http://docs.python.org/ref/calls.html

While having arguments after ** doesn't make sense,
comma after ANY kinds of arguments seem to be more
consistent.




----------------------------------------------------------------------

Comment By: Sean Gillespie (sean_gillespie)
Date: 2007-03-16 14:42

Message:
Logged In: YES 
user_id=1744567
Originator: NO

This behavior seems as intended.  According to the docs
(http://docs.python.org/ref/calls.html):

A trailing comma may be present after the positional and keyword arguments
but does not affect the semantics. 
[snip]
Formal parameters using the syntax "*identifier" or "**identifier" cannot
be used as positional argument slots or as keyword argument names.

I'm having trouble with what this actually means.  However, the relevant
section in the Grammar looks like this:

arglist: (argument ',')* (argument [',']| '*' test [',' '**' test] | '**'
test )

It looks like this logic was explicitly coded.

If this is determined to be a bug, we can just add [','] after the test in
both cases.

----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1531016&group_id=5470