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Subject: Re: suppressing import errors
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From: David Riley <fraveydank@gmail.com>
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Date: Tue, 15 Nov 2011 18:15:45 -0500
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To: Alan Meyer <ameyer2@yahoo.com>
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Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:15753

On Nov 15, 2011, at 5:59 PM, Alan Meyer wrote:

> On 11/15/2011 4:20 PM, David Riley wrote:
> ...
>>       None was set to some other value.  The other value might have a =
type
>>       (such as a container) that could be false in a boolean context!
>>=20
>> Obviously, that last bit doesn't apply to modules; they're not going =
to evaluate as False in general.  I just bristle when I see people =
writing "if x" when they really mean "if x is not None", perhaps because =
it's not The Right Way(tm)?  It mostly comes down to aesthetics, I =
guess.  Write what you really mean.
>=20
> Actually Dave, as your quote from PEP 8 says, the difference is real. =
It's not just aesthetics.

 I guess I meant it's aesthetics when it comes down to determining =
whether a module is None or not; a module is never going to evaluate to =
False under any feasible circumstances.  It's not an aesthetic =
difference when you consider that the global (or local) namespace may be =
polluted with other variables that have the same name as your module, =
but then your evaluation would be entirely invalid anyway.

But yes, in the general case, it's much more than an aesthetic =
difference, which is why I always write "if x is None" when I want to =
know if it's None (rather than False, 0, [], "", etc).  I have been =
bitten way too many times by doing the lazy thing to keep doing it.

- Dave