Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #84600

Re: Why does argparse return None instead of [] if an append action isn't used?

Show key headers only | View raw

Adam Funk wrote:

> On 2015-01-09, Ned Batchelder wrote:
> 
>> On 1/9/15 9:44 AM, Adam Funk wrote:
>>> This makes it a bit more trouble to use:
>>>
>>>    if options.bar:
>>>       for b in options:bar
>>>          do_stuff(b)
>>>
>>> instead of
>>>
>>>    for b in options.bar
>>>       do_stuff(b)
>>
>> This doesn't answer why the value defaults to None, and some people may
>> recoil at it, but I've used:
>>
>>      for b in options.bar or ():
>>          do_stuff(b)
> 
> Do you mean "for b in options.bar or []:" ?

Doesn't matter; in the context of a for loop any empty iterable would do.

Back to comp.lang.python | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Why does argparse return None instead of [] if an append action isn't used? Adam Funk <a24061@ducksburg.com> - 2015-01-09 14:44 +0000
  Re: Why does argparse return None instead of [] if an append action isn't used? Skip Montanaro <skip.montanaro@gmail.com> - 2015-01-09 08:57 -0600
    Re: Why does argparse return None instead of [] if an append action isn't used? Adam Funk <a24061@ducksburg.com> - 2015-01-09 15:25 +0000
  Re: Why does argparse return None instead of [] if an append action isn't used? Ned Batchelder <ned@nedbatchelder.com> - 2015-01-09 10:12 -0500
    Re: Why does argparse return None instead of [] if an append action isn't used? Adam Funk <a24061@ducksburg.com> - 2015-01-26 13:43 +0000
      Re: Why does argparse return None instead of [] if an append action isn't used? Peter Otten <__peter__@web.de> - 2015-01-26 15:04 +0100
        Re: Why does argparse return None instead of [] if an append action isn't used? Adam Funk <a24061@ducksburg.com> - 2015-01-26 15:50 +0000
          Re: Why does argparse return None instead of [] if an append action isn't used? Ian Kelly <ian.g.kelly@gmail.com> - 2015-01-26 09:13 -0700
            Re: Why does argparse return None instead of [] if an append action isn't used? Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2015-01-26 18:29 +0200
              Re: Why does argparse return None instead of [] if an append action isn't used? Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-01-26 17:18 +0000
              Re: Why does argparse return None instead of [] if an append action isn't used? Ian Kelly <ian.g.kelly@gmail.com> - 2015-01-26 11:23 -0700
              Re: Why does argparse return None instead of [] if an append action isn't used? Ian Kelly <ian.g.kelly@gmail.com> - 2015-01-26 11:26 -0700
  Re: Why does argparse return None instead of [] if an append action isn't used? Wolfgang Maier <wolfgang.maier@biologie.uni-freiburg.de> - 2015-01-09 16:50 +0100
    Re: Why does argparse return None instead of [] if an append action isn't used? Adam Funk <a24061@ducksburg.com> - 2015-01-26 13:43 +0000

csiph-web