no ordering method defined - Ruff

What it does

Checks for classes decorated with @functools.total_ordering that don't define any ordering method (__lt__, __le__, __gt__, or __ge__).

Why is this bad?

The @total_ordering decorator requires the class to define at least one ordering method. If none is defined, Python raises a ValueError at runtime.

Example

python

from functools import total_ordering


# no ordering method defined
@total_ordering  # error
class MyClass:
    def __eq__(self, other: object) -> bool:
        return True

Use instead:

python

from functools import total_ordering


@total_ordering
class MyClass:
    def __eq__(self, other: object) -> bool:
        return True

    def __lt__(self, other: "MyClass") -> bool:
        return True