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

Guido van Rossum guido at python.org
Mon Dec 13 23:16:58 CET 2010

On Mon, Dec 13, 2010 at 1:55 PM, Raymond Hettinger
<raymond.hettinger at gmail.com> wrote:
> On Dec 13, 2010, at 1:21 PM, Terry Reedy wrote:
>> Same here. A strong +1 for a consistent rule (always or never allowed) with a +1 for always given others use case of one param/arg per line.
> It seems to me that a trailing comma in an argument list is more likely to be a user error than a deliberate comma-for-the-future.

Really? Have you observed this? Even if it was inserted by mistake, it
is harmless. Python has a long tradition of allowing redundant
trailing commas in comma-separated lists, and it is habit-forming.
That's the issue the OP had: he expected it to work in the one context
where it doesn't.

--Guido van Rossum (python.org/~guido)

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