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From: Antoon Pardon <antoon.pardon@rece.vub.ac.be>
Newsgroups: comp.lang.python
Subject: Re: Operator Precedence/Boolean Logic
Date: Thu, 23 Jun 2016 13:15:32 +0200
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Xref: csiph.com comp.lang.python:110405

Op 23-06-16 om 12:59 schreef Marko Rauhamaa:
> Antoon Pardon <antoon.pardon@rece.vub.ac.be>:
>
>> Op 23-06-16 om 11:53 schreef Marko Rauhamaa:
>> Maybe something like this:
>>
>> def empty(sq):
>>     try:
>>         iter(sq).next()
>>     except StopIteration:
>>         return False
>>     except:
>>         raise TypeError
>>     else:
>>         return True
> That may or may not be as effective as a boolean check. The point is,
> Python has already declared that __bool__ is the canonical emptiness
> checker. You could even say that it's the principal purpose of the
> __bool__ method.

I think it is wrong to say __bool__ is the canonical emptiness checker.
It can be used for anything where you somehow think it is reasonable
to make a distinction between truthy and falsy. Even when talking
about emptyness doesn't make sense.

The function above at least raises an exception in a lot of cases
where the class provides booly behaviour yet emptyness wouldn't make
sense.

Would it be worth while? That you have to decide for yourself.

-- 
Antoon.