Class property, classmethod, ataticmethod methods and polymorphism

1. After property 

        defines a function of a class as a feature, when the object uses obj.name again, it is impossible to notice that its name is 
        calculated by executing a function. The use of this feature follows the unified access method. The principle 

        behind egon.bmi is a function, so it cannot be assigned 
            class People: 
                def __init__(self,name): 
                    self.__name=name 


                @property 
                def name(self): #obj.name 
                    print('What you are accessing now is Username...') 
                    return self.__name 

                @name.setter #obj.name='EGON' 
                def name(self,x): 
                    # print('================ ==',x) 
                    if type(x) is not str: 
                        raise TypeError('name must be str type, silly')
                    self.__name=x 

                @name.deleter 
                def name(self): 
                    # print('I won't let you delete') 
                    del self.__name 

            obj=People('egon') 

            print(obj.name) 
            print(obj.name( )) 

            print(obj.name) 

            obj.name='EGON' 

            print(obj.name) 

            obj.name=123 

            del obj.name 
            obj.name 


2. Polymorphism 
        Polymorphism refers to multiple forms of the same thing 
    2. Why use polymorphism 
        ? Create a set of unified rules with base classes and force subclasses to follow (implemented with abstract classes), so that you can 
        directly use the methods under the object without considering the specific type of the object. 


    3. How Using polymorphism 
         Polymorphism: you can directly use the methods under the object without considering the specific type of the object
        class Cat(Animal):
            def eat(self):
                print('cat eat')
        
            def drink(self):
                print('cat drink')
        
            def run(self):
                print('cat run')
        
            def bark(self):
                print('喵喵喵')
        
        class Dog(Animal):
            def eat(self):
                print('dog eat')
        
            def drink(self):
                print('dog drink')
        
            def run(self):
                print('dog run')
        
            def bark(self):
                print('汪汪汪')
        
        class Pig(Animal):
            def eat(self):
                print('pig eat') 
        
            def drink(self): 
                print('pig drink') 
        
            def run(self): 
                print('pig run') 
        
            def bark(self): 
                print('Hum hum') 
        
        c=Cat () 
        d=Dog() 
        p=Pig() 
  
        c.bark() 
        d.bark() 
        p.bark() 

    Note: 
      The abstract base class itself cannot be instantiated 

3. Binding method and non-binding method 

        1 Method: 
            The function defined inside the class is used by the object by default, and it is bound to the object, which is called the binding method of the 
            object. The method of binding the object is special: 
                it should be called by the object, and the object is called , the object will be automatically passed in as the first parameter 
        
            . The method bound to the class is special: 
                it should be called by the class, and when the class is called, the class will be automatically passed in as the first parameter
            
            import settings
            
            class People:
                def __init__(self,name,age):
                    self.name=name
                    self.age=age
            
                def tell(self):
                    print('%s：%s' %(self.name,self.age))
            
                @classmethod
                def from_conf(cls):
                    return cls(settings.NAME,settings.AGE)
            
            
            p=People('egon',19)
           
            print(People.from_conf)
            p4=People.from_conf(People)
            print(People.from_conf)
            p4=People.from_conf()
            p4.tell()
            
        
        2、staticmethod:非绑定方法，就是一个普通函数
        #Feature: It is neither bound to a class nor an object, which means that anyone can use it 
        # Anyone who uses it is an ordinary function, which means that there is no automatic value transfer feature 
            import settings 
            import hashlib 
            import time 
            
            class People: 
                def __init__(self,name,age): 
                    self.uid=self.create_id() self.name 
                    =name 
                    self.age=age 
            
                def tell(self): 
                    print('%s: %s: %s' %(self.uid,self.name,self.age)) 
            
                @classmethod 
                def from_conf(cls): 
                    return cls(settings.NAME,settings.AGE) 
            
                @staticmethod 
                def create_id():
                    m=hashlib.md5()
                    m.update(str(time.clock()).encode('utf-8'))
                    return m.hexdigest()
            
            obj=People('egon',18)
            print(obj.uid,obj.name,obj.age)
            obj.tell()
            
            print(obj.create_id)
            print(People.create_id)
            
            print(obj.create_id())
            print(People.create_id())