classmthod
Normal Python has classes which possess member functions (methods). Normal methods always take an initial parameter (usually called 'self') which refers to the instance of the class. For example:
class Ball(object):\n def __init__(self):\n self.x = 0\n\n def bounce(self, distance):\n self.x += distance\n\nbasketball = Ball()\nbasketball.bounce(3)
Inside 'bounce' (when we call it), 'self' refers to the basketball object instance, so you can manipulate it. Sometimes, however, you want a method which doesn't care about the instance, only the class. Often, these are constructors:
class Ball(object):\n def __init__(self):\n self.x = 0\n self.y = 0\n\n def displaced(cls, x, y):\n b = cls()\n b.x = x\n b.y = y\n return b\n displaced = classmethod(displaced)\n\nbasketball = Ball.displaced(3, 4)\nbasketball.bounce(3)
classmethod() takes what would have been a normal member function and makes it a class method. Class methods don't receive an instance as the first argument, but a class instead (classes are objects in Python). You have to pass in the class for the method to work on it. The above is pretty trivial--we could have just written b = Ball() instead of b = cls(), but once you start subclassing, you can take advantage of the generic nature of cls.
Hope that helped <:)
