python什么时候用类方法

class Kls(object):    num_inst = 0    def __init__(self):        Kls.num_inst = Kls.num_inst + 1    @classmethod    def get_no_of_instance(cls):        return cls.num_instik1 = Kls()ik2 = Kls()print ik1.get_no_of_instance()print Kls.get_no_of_instance()

coding:utf-8class Book(object):def __init__(self, title):self.title = title   @classmethoddef class_method_create(cls, title):book = cls(title=title)return book   @staticmethoddef static_method_create(title):book= Book(title)return bookbook1 = Book("use instance_method_create book instance")book2 = Book.class_method_create("use class_method_create book instance")book3 = Book.static_method_create("use static_method_create book instance")print(book1.title)print(book2.title)print(book3.title)