Negative form of isinstance() in Python

Question

How would I use a negative form of Python's isinstance()?

Normally negation would work something like

x != 1

if x not in y

if not a

I just haven't seen an example with isinstance(), so I'd like to know if there's a correct way to used negation with isinstance().

Tabernacle

So you don't mean not isinstance(...)? – Augsburg

so you need to learn how to use not for every python construction? – Incudes

This is still the Summer of Love, everyone. To be fair, that not in works shows that you don't need to have the not before the expression but sometimes it can float around a bit, and it's possible that there could have been a preferred Pythonic way other than not isinstance(). For example, there could have been some subtle corner case which meant you should use a different form (rather like type(obj) is list works sometimes but is suboptimal.) – Commensurate

There are two special forms: x is not y means the same as not(x is y), and x not in y means the same as not(x in y). – Mimeograph

Answer 1

Just use not. isinstance just returns a bool, which you can not like any other.

Linehan

Answer 2

That would seem strange, but:

if not isinstance(...):
   ...

The isinstance function returns a boolean value. That means that you can negate it (or make any other logical operations like or or and).

Example:

>>> a="str"
>>> isinstance(a, str)
True
>>> not isinstance(a, str)
False

Anacoluthon

Answer 3

Just use not, e.g.,

if not isinstance(someVariable, str):
     ....

You are simply negating the "truth value" (ie Boolean) that isinstance is returning.

Suggestible