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Re: Python's and and Pythons or

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On 10/10/2013 06:41 PM, Terry Reedy wrote:
> On 10/10/2013 9:33 AM, Ethan Furman wrote:
>
>> On 10/10/2013 12:43 AM, Terry Reedy wrote:
>
>>> On 10/10/2013 2:45 AM, Chris Angelico wrote:
>>>> first_element = some_list[0]    # Oops, may crash
>
>>> some_list[0:1] always works, and sometimes is usable, but you still
>>> cannot index the slice.
>
>> Not if some_list is None, False, or another non-indexable type.
>
> Did you really not understand that some_list is intended to be a list? Just like my_string, for instance, would be a
> string? Chris's statement further specifies some_list as a list that is expected to not be empty, but might be -- so one
> has to guard against the possibility.

I understood it just fine.  I'm also aware that at some point, in some program, it will be None (and it won't be a bug ;).


> The trick of slicing instead of indexing in this context is not obvious to everyone learning Python. Most other
> languages only have indexing. I learned the trick years ago when someone posted it on this list.

It's a good trick, I use it myself.

--
~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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