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Re: Python's and and Pythons or

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On 10/09/2013 11:12 PM, Peter Cacioppi wrote:
>
> I'm trying to think of a good example usage of echo-argument and. Maybe something like
>
> possible = foo and foo.allowsit()
> if (possible is None) :
>     print "foo not provided"
> if (possible is False) :
>     print "foo doesn't allow it"
>
> A bit awkward, echo-argument or is more naturally useful to me then echo-argument and.

It's used as a guard:

     if some_list and some_list[0] == something_or_other:
          do some_work()

Without the 'some_list and' portion when some_list was either empty or, say, None, the some_list[0] would fail with an 
error (IndexError, TypeError, etc.).

--
~Ethan~

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Thread

Python's and  and Pythons or Peter Cacioppi <peter.cacioppi@gmail.com> - 2013-10-09 16:54 -0700
  Re: Python's and  and Pythons or Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-10 00:36 +0000
    Re: Python's and and Pythons or Chris Angelico <rosuav@gmail.com> - 2013-10-10 12:13 +1100
  Re: Python's and  and Pythons or Peter Cacioppi <peter.cacioppi@gmail.com> - 2013-10-09 23:12 -0700
    Re: Python's and and Pythons or Chris Angelico <rosuav@gmail.com> - 2013-10-10 17:45 +1100
    Re: Python's and  and Pythons or Ethan Furman <ethan@stoneleaf.us> - 2013-10-09 23:46 -0700
    Re: Python's and and Pythons or Terry Reedy <tjreedy@udel.edu> - 2013-10-10 03:43 -0400
    Re: Python's and and Pythons or Chris Angelico <rosuav@gmail.com> - 2013-10-10 19:03 +1100
    Re: Python's and and Pythons or Ethan Furman <ethan@stoneleaf.us> - 2013-10-10 06:33 -0700
    Re: Python's and and Pythons or Terry Reedy <tjreedy@udel.edu> - 2013-10-10 21:41 -0400
    Re: Python's and and Pythons or Ethan Furman <ethan@stoneleaf.us> - 2013-10-10 19:47 -0700
  Re: Python's and  and Pythons or Peter Cacioppi <peter.cacioppi@gmail.com> - 2013-10-09 23:55 -0700

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