Re: hasattr() or "x in y"?

From	Chris Angelico <rosuav@gmail.com>
Newsgroups	comp.lang.python
Subject	Re: hasattr() or "x in y"?
Date	2016-03-12 09:04 +1100
Message-ID	<mailman.11.1457733894.12893.python-list@python.org> (permalink)
References	<nbve7c$nbo$1@dont-email.me> <nbvep7$pb3$1@dont-email.me>

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On Sat, Mar 12, 2016 at 8:53 AM, Charles T. Smith
<cts.private.yahoo@gmail.com> wrote:
> On Fri, 11 Mar 2016 21:44:27 +0000, Charles T. Smith wrote:
>
>> From the performance point of view, which is better: - hasattr()
>> - x in y
>>
>> TIA
>> cts
>
>
> I just realized that "in" won't look back through the class hierarchy...
> that clearly makes them not interchangable, but given we're only
> interested in the current dict...

They're still completely different - hasattr looks at attributes, but
the 'in' operator looks at the object's members (in the case of a
dictionary, the keys). There is a broad similarity between
"hasattr(obj, attrname)" and "attrname in obj.__dict__", but if you're
doing the latter, you have other problems than performance; attributes
should be looked up as attributes, not as dictionary members.

ChrisA

Thread

hasattr() or "x in y"? "Charles T. Smith" <cts.private.yahoo@gmail.com> - 2016-03-11 21:44 +0000
  Re: hasattr() or "x in y"? Chris Angelico <rosuav@gmail.com> - 2016-03-12 08:55 +1100
  Re: hasattr() or "x in y"? "Charles T. Smith" <cts.private.yahoo@gmail.com> - 2016-03-11 21:53 +0000
    Re: hasattr() or "x in y"? Chris Angelico <rosuav@gmail.com> - 2016-03-12 09:04 +1100
    Re: hasattr() or "x in y"? Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-11 22:05 +0000
  Re: hasattr() or "x in y"? Grant Edwards <invalid@invalid.invalid> - 2016-03-11 22:00 +0000
    Re: hasattr() or "x in y"? "Charles T. Smith" <cts.private.yahoo@gmail.com> - 2016-03-11 22:18 +0000
      Re: hasattr() or "x in y"? Grant Edwards <invalid@invalid.invalid> - 2016-03-11 22:30 +0000

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