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From: Christian Heimes <lists@cheimes.de>
Subject: Re: Equivalent code to the bool() built-in function
Date: Tue, 19 Apr 2011 03:39:50 +0200
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Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:3517

Am 18.04.2011 21:58, schrieb John Nagle:
>     This is typical for languages which backed into a "bool" type,
> rather than having one designed in.  The usual result is a boolean
> type with numerical semantics, like
> 
>  >>> True + True
> 2

I find the behavior rather useful. It allows multi-xor tests like:

if a + b + c + d != 1:
    raise ValueError("Exactly one of a, b, c or d must be true.")

Christian