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Groups > comp.lang.python > #82405

Re: Extension of while syntax

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Nelson Crosby <nc@sourcecomb.com> writes:

> I was thinking a bit about the following pattern:
>
> value = get_some_value()
> while value in undesired_values:
>     value = get_some_value()

I think that's an anti-pattern (because of the repetition, as you say).

An improvement::

    value = some_default_value_such_as_None
    while value in undesired_values:
        value = get_some_value()

More common and generally useful::

    while True:
        value = get_some_value()
        if value not in undesired_values:
            break

> What are other's thoughts on this?

I think there are already clean ways to deal with this in common use.

<URL:https://wiki.python.org/moin/WhileLoop>
<URL:https://docs.python.org/3/tutorial/controlflow.html#break-and-continue-statements-and-else-clauses-on-loops>

-- 
 \       “… one of the main causes of the fall of the Roman Empire was |
  `\        that, lacking zero, they had no way to indicate successful |
_o__)                  termination of their C programs.” —Robert Firth |
Ben Finney

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Extension of while syntax Nelson Crosby <nc@sourcecomb.com> - 2014-12-11 18:21 -0800
  Re: Extension of while syntax Ben Finney <ben+python@benfinney.id.au> - 2014-12-12 13:37 +1100
  Re: Extension of while syntax Chris Angelico <rosuav@gmail.com> - 2014-12-12 13:38 +1100
    Re: Extension of while syntax Marko Rauhamaa <marko@pacujo.net> - 2014-12-12 09:10 +0200
      Re: Extension of while syntax Chris Angelico <rosuav@gmail.com> - 2014-12-12 18:38 +1100
        Re: Extension of while syntax Marko Rauhamaa <marko@pacujo.net> - 2014-12-12 10:25 +0200
      Re: Extension of while syntax cl@isbd.net - 2014-12-12 09:09 +0000
        Re: Extension of while syntax Marko Rauhamaa <marko@pacujo.net> - 2014-12-12 12:33 +0200
  RE: Extension of while syntax "Clayton Kirkwood" <crk@godblessthe.us> - 2014-12-11 18:59 -0800
  Re: Extension of while syntax Terry Reedy <tjreedy@udel.edu> - 2014-12-11 22:00 -0500
  Re: Extension of while syntax Ben Finney <ben+python@benfinney.id.au> - 2014-12-12 14:14 +1100
  Re: Extension of while syntax Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-12-12 08:00 +0000
  Re: Extension of while syntax Chris Angelico <rosuav@gmail.com> - 2014-12-12 19:05 +1100
  Re: Extension of while syntax Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-12-12 11:38 -0500
  Re: Extension of while syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-13 22:56 +1100

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