`A()` is not a class

What it does

Detects super() calls where:

• the first argument is not a valid class literal, or
• the second argument is not an instance or subclass of the first argument.

Why is this bad?

super(type, obj) expects:

• the first argument to be a class,
• and the second argument to satisfy one of the following:
  • isinstance(obj, type) is True
  • issubclass(obj, type) is True

Violating this relationship will raise a TypeError at runtime.

Examples

class A: ...


class B(A): ...


super(A, B())  # it's okay! `A` satisfies `isinstance(B(), A)`

# `A()` is not a class
super(A(), B())  # error

# `A()` does not satisfy `isinstance(A(), B)`
super(B, A())  # error
# `A` does not satisfy `issubclass(A, B)`
super(B, A)  # error

References

• Python documentation: super()