Checking whether type is None
steve+comp.lang.python at pearwood.info
Tue Jul 24 19:02:11 EDT 2018
On Tue, 24 Jul 2018 12:33:27 -0700, Tobiah wrote:
> So what would I compare type(None) to?
Why would you need to? The fastest, easiest, most reliable way to check
if something is None is:
if something is None
> >>> type(None)
> <type 'NoneType'>
> >>> type(None) is NoneType
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> NameError: name 'NoneType' is not defined
You can do:
from types import NoneType
or if you prefer:
NoneType = type(None)
but why bother?
> I know I ask whether:
> >>> thing is None
> but I wanted a generic test.
That *is* a generic test.
> I'm trying to get away from things like:
> >>> type(thing) is type(None)
That is a good move.
> because of something I read somewhere preferring my original test
Oh, you read "something" "somewhere"? Then it must be good advice!
Writing code like:
type(something) is dict
was the standard way to do a type check back in the Python 1.5 days.
That's about 20 years ago now. These days, that is rarely what we need
The usual way to check a type is:
but even that should be rare. If you find yourself doing lots of type
checking, using isinstance() or type(), then you're probably writing
slow, inconvenient Python code.
"Ever since I learned about confirmation bias, I've been seeing
it everywhere." -- Jon Ronson
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