[Python-Dev] Multi-line import implementation (was: 2.4a2, and @decorators) (original) (raw)

Michael Chermside mcherm at mcherm.com
Wed Aug 11 15:57:41 CEST 2004

My patch (attached) accepts

import (os, sys) from sys import (stdin, stdout, stderr) import (os) from sys import (*) but rejects from (sys) import stdin import (os), (sys) import (os,) Should any of those be allowed? Anything that I missed?

Others have already mentioned that "from sys import xxx, xxx, xxx" is the case that badly needs line wrapping. I would, however, like to suggest that (if it's easy to do) you allow a trailing comma when parenthesees are used. Of course this looks silly:

from mymodule import (xxx, xxx, xxx, xxx,)

But in the most extreme case, like this:

from myBigModule import ( xxxxxxxx, xxxxxxxx, xxxxxxxx, xxxxxxxx, xxxxxxxx, xxxxxxxx, xxxxxxxx, xxxxxxxx, xxxxxxxx, xxxxxxxx, xxxxxxxx, xxxxxxxx, xxxxxxxx, xxxxxxxx, xxxxxxxx, )

it's awefully nice on cut-and-paste to allow the trailing comma. But the most important reason for doing so is that Python already allows (and disregards) an extra trailing comma in similar lists:

>>> [1,2,3,]
[1, 2, 3]
>>> {1:1,2:2,3:3,}
{1: 1, 2: 2, 3: 3}
>>> def func(a,b,c,):
...     print a, b, c
...
>>> func(1,2,3)
1 2 3
>>> (1,2,3,)
(1, 2, 3)

-- Michael Chermside

PS: The length-one-tuple is a special case (and a bit of a wart) in that it MANDATES the use of the trailing comma. But that's got nothing to do with the basic principle.

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