一般來說，要使用某個類的方法，需要先實例化一個對象再調用方法。

而使用@staticmethod或@classmethod，就可以不需要實例化，直接類名.方法名()來調用。

這有利于組織代碼，把某些應該屬于某個類的函數給放到那個類里去，同時有利于命名空間的整潔。

既然@staticmethod和@classmethod都可以直接類名.方法名()來調用，那他們有什么區別呢

從它們的使用上來看

如果在@staticmethod中要調用到這個類的一些屬性方法，只能直接類名.屬性名或類名.方法名。

而@classmethod因為持有cls參數，可以來調用類的屬性，類的方法，實例化對象等，避免硬編碼。

要明白，什么是實例方法、靜態方法和類方法：

class Demo(object): 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)

雖然類方法在調用的時候沒有顯式聲明cls，但實際上類本身是作為隱含參數傳入的。這就像實例方法在調用的時候也沒有顯式聲明self,但實際上實例本身是作為隱含參數傳入的。

對于靜態函數，我們一般把與類無關也與實例無關的函數定義為靜態函數。例如入口檢查的函數就最好定義成靜態函數。

類方法的妙處， 在繼承中的作用：

class Fruit(object): total = 0 # 這是一個類屬性 @classmethod def print_total(cls): print('this is the ', cls, '.total:', cls.total, ' and its id: ', id(cls.total)) # cls是類本身，打印類屬性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 = valueclass Apple(Fruit): passclass Orange(Fruit): passapp1 = 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: 1355201264this is the Fruit.total: 0 and its id: 1355200944=======================this is the <class '__main__.Apple'> .total: 10 and its id: 1355201264this is the Fruit.total: 0 and its id: 1355200944=======================this is the <class '__main__.Apple'> .total: 10 and its id: 1355201264this is the Fruit.total: 2 and its id: 1355201008=======================this is the <class '__main__.Fruit'> .total: 2 and its id: 1355201008this is the Fruit.total: 2 and its id: 1355201008======================="""