[Python-Dev] A grammatical oddity: trailing commas in argument lists -- continuation

Glenn Linderman v+python at g.nevcal.com
Mon Dec 13 20:26:44 CET 2010

On 12/13/2010 11:17 AM, Antoine Pitrou wrote:
> On Mon, 13 Dec 2010 14:09:02 -0500
> Alexander Belopolsky<alexander.belopolsky at gmail.com>  wrote:
>> On Mon, Dec 13, 2010 at 11:54 AM, Guido van Rossum<guido at python.org>  wrote:
>>> I'm at least +0 on
>>> allowing trailing commas in the situation the OP mentioned.
>> FWIW, I am also about +0.5 on allowing trailing comma.  Note that in a
>> similar situation,  the C standardization committee has erred on the
>> side of consistency:
>> """
>> A new feature of C99: a common extension in many implementations
>> allows a trailing comma after the list of enumeration constants. The
>> Committee decided to adopt this feature as an innocuous extension that
>> mirrors the trailing commas allowed in initializers.
>> """ http://www.open-std.org/jtc1/sc22/wg14/www/C99RationaleV5.10.pdf
>> Similarly, I find allowing trailing comma in keyword only arguments
>> lists to be an innocuous extension that mirrors the trailing commas
>> allowed in the positional arguments lists.
> +1 from me as well. Special cases are hard to remember.

+1.  I tend to put them in, and then take out the ones that Python won't 
Then, when I add another item to the list, Python tells me to go back 
and put the one I took out back in again, and take out the one I put in 
at the new end of the list.  Annoying.  (for vertically arranged lists, 
one per line, primarily, with ) on the last line by itself.
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