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
