duplicate-bases (PLE0241)

Derived from the Pylint linter.

Fix is sometimes available.

What it does

Checks for duplicate base classes in class definitions.

Why is this bad?

Including duplicate base classes will raise a TypeError at runtime.

Example

class Foo:
    pass


class Bar(Foo, Foo):
    pass

Use instead:

class Foo:
    pass


class Bar(Foo):
    pass

Fix safety

This rule's fix is marked as unsafe if there's comments in the base classes, as comments may be removed.

For example, the fix would be marked as unsafe in the following case:

class Foo:
    pass


class Bar(
    Foo,  # comment
    Foo,
):
    pass

References

• Python documentation: Class definitions