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Groups > comp.lang.python > #90152

Re: Is this unpythonic?

Date 2015-05-08 08:04 -0400
From Dave Angel <davea@davea.name>
Subject Re: Is this unpythonic?
References <mailman.224.1431072121.12865.python-list@python.org> <554c8b0a$0$12992$c3e8da3$5496439d@news.astraweb.com> <mii4il$vv$1@ger.gmane.org>
Newsgroups comp.lang.python
Message-ID <mailman.239.1431086688.12865.python-list@python.org> (permalink)

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On 05/08/2015 06:53 AM, Frank Millman wrote:
>
> "Steven D'Aprano" <steve+comp.lang.python@pearwood.info> wrote in message
> news:554c8b0a$0$12992$c3e8da3$5496439d@news.astraweb.com...
>> On Fri, 8 May 2015 06:01 pm, Frank Millman wrote:
>>
>>> Hi all
>>>
> [...]
>>>
>>> However, every time I look at my own code, and I see   "def x(y, z=[]):
>>> ....."   it looks wrong because I have been conditioned to think of it as
>>> a gotcha.
>>

It might be appropriate to define the list at top-level, as

EMPTY_LIST=[]

and in your default argument as
     def x(y, z=EMPTY_LIST):

and with the all-caps, you're thereby promising that nobody will modify 
that list.

(I'd tend to do the None trick, but I think this alternative would be 
acceptable)

-- 
DaveA

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Thread

Is this unpythonic? "Frank Millman" <frank@chagford.com> - 2015-05-08 10:01 +0200
  Re: Is this unpythonic? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-05-08 20:08 +1000
    Re: Is this unpythonic? "Frank Millman" <frank@chagford.com> - 2015-05-08 12:53 +0200
      Re: Is this unpythonic? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-05-09 01:07 +1000
        Re: Is this unpythonic? "Frank Millman" <frank@chagford.com> - 2015-05-09 07:56 +0200
        Re: Is this unpythonic? "Frank Millman" <frank@chagford.com> - 2015-05-09 08:51 +0200
          Re: Is this unpythonic? Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-05-09 19:47 +1200
            Re: Is this unpythonic? "Frank Millman" <frank@chagford.com> - 2015-05-09 11:10 +0200
    Re: Is this unpythonic? Dave Angel <davea@davea.name> - 2015-05-08 08:04 -0400
      Re: Is this unpythonic? Johannes Bauer <dfnsonfsduifb@gmx.de> - 2015-05-10 10:04 +0200
        Re: Is this unpythonic? "Frank Millman" <frank@chagford.com> - 2015-05-10 10:58 +0200
          Re: Is this unpythonic? Johannes Bauer <dfnsonfsduifb@gmx.de> - 2015-05-10 11:54 +0200
            Re: Is this unpythonic? "Frank Millman" <frank@chagford.com> - 2015-05-10 12:40 +0200
    Re: Is this unpythonic? "Frank Millman" <frank@chagford.com> - 2015-05-08 15:12 +0200

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