AttributeError: 'A' object has no attribute 'foo'

What it does

Checks for unresolved attributes.

Why is this bad?

Accessing an unbound attribute will raise an AttributeError at runtime. An unresolved attribute is not guaranteed to exist from the type alone, so this could also indicate that the object is not of the type that the user expects.

Examples

class A: ...


# AttributeError: 'A' object has no attribute 'foo'
A().foo  # error