Python中staticmethod和classmethod的作用与区别

class Demo( ):
  def instance_method(self, your_para):
    """
    this is an instance_method
    you should call it like the follow:
    a = Demo()
    a.instance_method(your_para)
    plus: in python, we denote 'cls' as latent para of Class
    while 'self' as latent para of the instance of the Class
    :param your_para: 
    :return: 
    """
    print("call instance_method and get:", your_para)
  @classmethod
  def class_method(cls, your_para):
    """
    this is a class_method
    you can call it like the follow:
    method1:
    a = Demo()
    a.class_method(your_para)
    method2:
    Demo.class_method
   plus: in python, we denote 'cls' as latent para of Class
    while 'self' as latent para of the instance of the Class
    :param your_para: 
    :return: 
    """
    print("call class_method and get:", your_para)
  @staticmethod
  def static_method(your_para):
    """
    this is a static_method and you can call it like the 
    methods of class_method
    :param your_para: 
    :return: 
    """
    print("call static_method and get:", your_para)12345678910111213141516171819202122232425262728293031323334353637383940414243444546

class Fruit( ):
  total = 0  # 这是一个类属性
  @classmethod
  def print_total(cls):
    print('this is the ', cls, '.total:', cls.total, ' and its id: ', id(cls.total))  # cls是类本身，打印类属性total的值
    print('this is the Fruit.total:', Fruit.total, 'and its id: ', id(Fruit.total))
    print("=======================")
  @classmethod
  def set(cls, value):
    cls.total = value
class Apple(Fruit):
  pass
class Orange(Fruit):
  pass
app1 = Apple()
app1.set(10)
app1.print_total()
Apple.print_total()
Fruit.set(2)
app1.print_total()
Fruit.print_total()
"""
output:
this is the <class '__main__.Apple'> .total: 10 and its id: 1355201264
this is the Fruit.total: 0 and its id: 1355200944
=======================
this is the <class '__main__.Apple'> .total: 10 and its id: 1355201264
this is the Fruit.total: 0 and its id: 1355200944
=======================
this is the <class '__main__.Apple'> .total: 10 and its id: 1355201264
this is the Fruit.total: 2 and its id: 1355201008
=======================
this is the <class '__main__.Fruit'> .total: 2 and its id: 1355201008
this is the Fruit.total: 2 and its id: 1355201008
=======================
"""