none-comparison (E711)

Added in v0.0.28 · Related issues · View source

Derived from the pycodestyle linter.

Fix is always available.

What it does

Checks for comparisons to None which are not using the is operator.

Why is this bad?

According to PEP 8, "Comparisons to singletons like None should always be done with is or is not, never the equality operators."

Example

if arg != None:
    pass
if None == arg:
    pass

Use instead:

if arg is not None:
    pass

Fix safety

This rule's fix is marked as unsafe, as it may alter runtime behavior when used with libraries that override the ==/__eq__ or !=/__ne__ operators. In these cases, is/is not may not be equivalent to ==/!=. For more information, see this issue.