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Date: Thu, 10 Oct 2013 17:45:49 +1100
Subject: Re: Python's and and Pythons or
From: Chris Angelico <rosuav@gmail.com>
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Xref: csiph.com comp.lang.python:56547

On Thu, Oct 10, 2013 at 5:12 PM, Peter Cacioppi
<peter.cacioppi@gmail.com> 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.

first_element = some_list[0]    # Oops, may crash

try:
    first_element = some_list[0]
except IndexError:
    firstelement = None   # A bit verbose

first_element = some_list and some_list[0]

# or if you want a zero instead of an empty list:
first_element = len(some_list) and some_list[0]


Also, consider the case where you have a function, or None:

result = func(*args,**kwargs)   # NoneType is not callable

result = func and func(*args,**kwargs)

ChrisA