The first argument to class methods should follow the naming convention

By convention, the first argument to class methods, i.e. methods decorated with @classmethod, is named cls as a representation and a reminder that the argument is the class itself. Name the argument something else, and you stand a good chance of confusing both users and maintainers of the code. It might also indicate that the cls parameter was forgotten, in which case calling the method will most probably fail. This rule also applies to methods __init_subclass__, __class_getitem__ and __new__ as their first argument is always the class instead of "self".

By default this rule accepts cls and mcs, which is sometime used in metaclasses, as valid names for class parameters. You can set your own list of accepted names via the parameter classParameterNames.

This rule raises an issue when the first parameter of a class method is not an accepted name.

Noncompliant Code Example

class Rectangle(object):

  @classmethod
  def area(bob, height, width):  #Noncompliant
    return height * width

Compliant Solution

class Rectangle(object):

  @classmethod
  def area(cls, height, width):
    return height * width

See

• PEP8 - Function and Method Arguments