Five, Python 5 facing the object, the class methods, and static methods

5, class methods, and static methods

Description : class methods and static methods similar, they are recommended to use class to call (available objects to call)

1) Class Methods

The definition of class method :

• Use @classmethod modified
• The first parameter is defined as a method cls, this method is invoked by the class parameter are automatically bound

class Tiger:
    # 类方法：1、用 @classmethod 修饰；2、定义 cls 形参
    @classmethod
    def info(cls):
        print('info类方法')
        print(cls)
        
print(Tiger)
print('-'*30)

Tiger.info()     # 类方法属于类本身，可用类调用。类方法的第一个参数 cls 绑定到调用该方法的类
print('-'*30)

t = Tiger()
t.info()         # 对象调用类方法，实际上也相当于用类调用类方法，同样也会执行将第一个参数绑定当前类

<class '__main__.Tiger'>
------------------------------
info类方法
<class '__main__.Tiger'>
------------------------------
info类方法
<class '__main__.Tiger'>

Compare :

• Whether it is a class method invocation or class instance calls are automatically bound
• Examples of the method when the object is automatically bound with the call when the call is not automatically bound by class, parameter passing requires

2) static method

Define a static method :

• Use @staticmethod modified

• Static method is equivalent to a function, not automatically binding

  class Tiger:
      # 静态方法：用 @staticmethod
      @staticmethod
      def info1():
          print('info1静态方法')
      
      @staticmethod  
      def info2(p):
          print('info2静态方法')
          print(p)
  

  • Class static method call

    Tiger.info1()             # 类调用静态方法（无参数时）
    print('-'*30)
    
    Tiger.info2('python')     # 类调用静态方法（有参数时），需要传入参数
    

    info1静态方法
    ------------------------------
    info2静态方法
    python
    

  • Object calls the static method

    t = Tiger()
    
    t.info1()          # 对象调用静态方法（无参数时）
    print('-'*30)
    
    t.info2('python')  # 对象调用静态方法（有参数时），需要传入参数
    print('-'*30)
    

    info1静态方法
    ------------------------------
    info2静态方法
    python
    

3) Summary:

	Examples of methods	Class Methods	Static method
Object calls	Automatic Binding	Automatic Binding	Do not automatically binding
Class call	Do not automatically binding	Automatic Binding	Do not automatically binding