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Re: Is vars() the most useless Python built-in ever?

From Peter Otten <__peter__@web.de>
Newsgroups comp.lang.python
Subject Re: Is vars() the most useless Python built-in ever?
Date 2015-12-02 08:51 +0100
Organization None
Message-ID <mailman.101.1449042757.14615.python-list@python.org> (permalink)
References <565cf141$0$1612$c3e8da3$5496439d@news.astraweb.com> <mailman.57.1448960191.14615.python-list@python.org> <565e459b$0$1615$c3e8da3$5496439d@news.astraweb.com>

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Steven D'Aprano wrote:

> and your code will break. Better and safer is:
> 
> 
> def main():  # parse the args and call whatever function was selected
>     args = parser.parse_args(sys.argv[1:])
>     try:
>         func = args.func
>     except AttributeError as err:
>         parser.print_help()
>     else:
>         func(vars(args))

I don't think this is any better. You are reponding on a programming error 
in the script as if the user had provided erroneous input. Very confusing.
Just

    args.func(vars(args))

will produce a traceback if the programmer made an error and a help message 
if the user provides arguments that are not recognized. 

That's how it should be.

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Thread

Is vars() the most useless Python built-in ever? Steven D'Aprano <steve@pearwood.info> - 2015-12-01 12:00 +1100
  Re: Is vars() the most useless Python built-in ever? Josef Pktd <josef.pktd@gmail.com> - 2015-11-30 19:45 -0800
  Re: Is vars() the most useless Python built-in ever? Rick Johnson <rantingrickjohnson@gmail.com> - 2015-11-30 21:54 -0800
    Re: Is vars() the most useless Python built-in ever? Marko Rauhamaa <marko@pacujo.net> - 2015-12-01 09:34 +0200
      Re: Is vars() the most useless Python built-in ever? Rick Johnson <rantingrickjohnson@gmail.com> - 2015-12-11 13:06 -0800
    Re: Is vars() the most useless Python built-in ever? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-12-01 18:55 +1100
      Re: Is vars() the most useless Python built-in ever? Rick Johnson <rantingrickjohnson@gmail.com> - 2015-12-01 12:33 -0800
        Re: Is vars() the most useless Python built-in ever? Steven D'Aprano <steve@pearwood.info> - 2015-12-02 11:57 +1100
        Re: Is vars() the most useless Python built-in ever? Ian Kelly <ian.g.kelly@gmail.com> - 2015-12-01 22:48 -0600
          Re: Is vars() the most useless Python built-in ever? Rick Johnson <rantingrickjohnson@gmail.com> - 2015-12-11 14:13 -0800
            Re: Is vars() the most useless Python built-in ever? Steven D'Aprano <steve@pearwood.info> - 2015-12-12 15:44 +1100
              Re: Is vars() the most useless Python built-in ever? Chris Angelico <rosuav@gmail.com> - 2015-12-12 16:56 +1100
              Re: Is vars() the most useless Python built-in ever? Rick Johnson <rantingrickjohnson@gmail.com> - 2015-12-14 18:33 -0800
      Re: Is vars() the most useless Python built-in ever? Ben Finney <ben+python@benfinney.id.au> - 2015-12-02 12:47 +1100
    Re: Is vars() the most useless Python built-in ever? John Gordon <gordon@panix.com> - 2015-12-01 16:56 +0000
      Re: Is vars() the most useless Python built-in ever? Rick Johnson <rantingrickjohnson@gmail.com> - 2015-12-01 13:15 -0800
        Re: Is vars() the most useless Python built-in ever? "Albert Visser" <albert.visser@gmail.com> - 2015-12-02 19:08 +0100
    Re: Is vars() the most useless Python built-in ever? Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-12-02 13:14 +1300
  Re: Is vars() the most useless Python built-in ever? eryk sun <eryksun@gmail.com> - 2015-12-01 01:22 -0600
    Re: Is vars() the most useless Python built-in ever? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-12-01 18:57 +1100
  Re: Is vars() the most useless Python built-in ever? Manolo Martínez <manolo@austrohungaro.com> - 2015-12-01 09:44 +0100
    Re: Is vars() the most useless Python built-in ever? Steven D'Aprano <steve@pearwood.info> - 2015-12-02 12:12 +1100
      Re: Is vars() the most useless Python built-in ever? Peter Otten <__peter__@web.de> - 2015-12-02 08:51 +0100
  Re: Is vars() the most useless Python built-in ever? Peter Otten <__peter__@web.de> - 2015-12-01 11:40 +0100
  Re: Is vars() the most useless Python built-in ever? Manolo Martínez <manolo@austrohungaro.com> - 2015-12-01 22:31 +0100
  Re: Is vars() the most useless Python built-in ever? Peter Otten <__peter__@web.de> - 2015-12-01 23:41 +0100
  Re: Is vars() the most useless Python built-in ever? boB Stepp <robertvstepp@gmail.com> - 2015-12-01 20:20 -0600
  Re: Is vars() the most useless Python built-in ever? wxjmfauth@gmail.com - 2015-12-01 23:46 -0800
  Re: Is vars() the most useless Python built-in ever? Serhiy Storchaka <storchaka@gmail.com> - 2015-12-02 10:22 +0200
  Re: Is vars() the most useless Python built-in ever? Manolo Martínez <manolo@austrohungaro.com> - 2015-12-02 10:09 +0100
  Re: Is vars() the most useless Python built-in ever? Chris Angelico <rosuav@gmail.com> - 2015-12-02 20:28 +1100
  Re: Is vars() the most useless Python built-in ever? Chris Angelico <rosuav@gmail.com> - 2015-12-02 20:33 +1100
  Re: Is vars() the most useless Python built-in ever? Manolo Martínez <manolo@austrohungaro.com> - 2015-12-02 10:40 +0100
  Re: Is vars() the most useless Python built-in ever? Peter Otten <__peter__@web.de> - 2015-12-02 11:48 +0100
  Re: Is vars() the most useless Python built-in ever? Chris Angelico <rosuav@gmail.com> - 2015-12-02 22:02 +1100
  Re: Is vars() the most useless Python built-in ever? eryk sun <eryksun@gmail.com> - 2015-12-02 05:34 -0600
  Re: Is vars() the most useless Python built-in ever? Serhiy Storchaka <storchaka@gmail.com> - 2015-12-04 10:42 +0200

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