Forbid incorrect __slots__ names

[sobolevn]

Rule request

Thesis

We need to lint names in slots. Rules are:

• names are non-empty
• they should be valid python identifiers
• they should have valid attribute names (snake_case) we can reuse logic from pep8-naming

Reasoning

Otherwise names defined in __slots__ will be incorrect and will result in incorrect objects.
This is OOP rule

[sobolevn]

By the way, python already handles this case:

class Test(object):
    a = 1

    __slots__ = ('a', 'b')

Will result in:

Traceback (most recent call last):
  File "ex.py", line 1, in <module>
    class Test(object):
ValueError: 'a' in __slots__ conflicts with class variable