isinstance-type-none (FURB168)

Derived from the refurb linter.

Fix is sometimes available.

This rule is unstable and in preview. The --preview flag is required for use.

What it does

Checks for uses of isinstance that check if an object is of type None.

Why is this bad?

There is only ever one instance of None, so it is more efficient and readable to use the is operator to check if an object is None.

Example

isinstance(obj, type(None))

Use instead:

obj is None

References

• Python documentation: isinstance
• Python documentation: None
• Python documentation: type
• Python documentation: Identity comparisons