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Date: Tue, 19 Apr 2011 16:26:50 +1000
Subject: Re: Equivalent code to the bool() built-in function
From: Chris Angelico <rosuav@gmail.com>
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Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:3542

On Tue, Apr 19, 2011 at 4:23 PM, Kushal Kumaran
<kushal.kumaran+python@gmail.com> wrote:
>> if a + b + c + d !=3D 1:
>> =A0 =A0raise ValueError("Exactly one of a, b, c or d must be true.")
>>
>
> Unless you're sure all of a, b, c, and d are boolean values, an int
> with a negative value slipping in could result in the sum equaling 1,
> but more than one of the variables evaluating to True in boolean
> contexts.

If they're all expressions, then you can easily guarantee that.

ChrisA