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

Glenn Linderman v+python at g.nevcal.com
Mon Dec 13 21:08:31 CET 2010

On 12/13/2010 11:39 AM, Mark Dickinson wrote:
> my_thing = Thing(
>      foo = Foo(arg1, arg2, ...),
>      bar = Bar(arg3, arg4, ...),
>      ...
> )
> and I've found the trailing comma very convenient during refactoring
> and API experimentation.  (There's still good fun to be had arguing
> about the indentation of that closing parenthesis, though.)

Clearly it needs to be indented one level, because it is a continuation 
of the prior line, just like the foo and bar and ... lines are 
continuations and therefore indented.

I'd have argued differently for languages that use {} to delimit blocks.


More information about the Python-Dev mailing list