"Python" detailed class Method: Instance method, class method, static method (iii)

in a class, there may be three methods, instance methods, static methods, and class methods, and here's how the three approaches differ:

1 . The first argument of an instance method instance method must be "self", and the instance method can only be invoked through a class instance, at which point "Self" represents the instance itself . the properties of an instance can be accessed directly through "self" .

class Person (object):
    tall = 180
    Hobbies = []
    def __init__ (self, Name, age,weight):
        self.name = name
        Self.age = age
        self.weight = weight
    def infoma (self):
        print ('%s '%s weights%s '% (Self.name, self.age,self.weight))


Bruce = Person ("Bruce", 25,180)
Bruce.infoma ()

Output:

Bruce is weights 180

2. Class method class methods use the CLS as the first parameter , theCLS represents the class itself , and the @classmethod adorner is defined. The CLS can access the related properties of the class.

class Person (object):

    tall = 180
    Hobbies = []
    def __init__ (self, Name, age,weight):
        self.name = name
        Self.age = age
        self.weight = weight
    @classmethod     #类的装饰器
    def infoma (CLS):   #cls表示类本身, Use the class parameter CLS
        print (cls.__name__)
        print (dir (CLS))
#cls表示类本身
#person. Infoma ()  directly call the adorner function of the class. The CLS can access the related properties of a class
Bruce = Person ("Bruce", 25,180)   #也可以通过两步骤来实现, the first instance of the person is instantiated, and the second step is to invoke the adorner

The output of the code, as you can see from this code, is that the class method can be accessed through the class name or through an instance :

Person
[' __class__ ', ' __delattr__ ', ' __dict__ ', ' __dir__ ', ' __doc__ ', ' __eq__ ', ' __format__ ', ' __ge__ ', ' __ getattribute__ ', ' __gt__ ', ' __hash__ ', ' __init__ ', ' __le__ ', ' __lt__ ', ' __module__ ', ' __ne__ ', ' __new__ ', ' __reduce__ ', ' __reduce_ex__ ', ' __repr__ ', ' __setattr__ ', ' __sizeof__ ', ' __str__ ', ' __subclasshook__ ', ' __weakref__ ', ' hobbies ', ' Infoma ', ' tall ']
person
[' __class__ ', ' __delattr__ ', ' __dict__ ', ' __dir__ ', ' __doc__ ', ' __eq__ ', ' __format__ ' , ' __ge__ ', ' __getattribute__ ', ' __gt__ ', ' __hash__ ', ' __init__ ', ' __le__ ', ' __lt__ ', ' __module__ ', ' __ne__ ', ' __new__ ', ' __reduce__ ', ' __reduce_ex__ ', ' __repr__ ', ' __setattr__ ', ' __sizeof__ ', ' __str__ ', ' __subclasshook__ ', ' __weakref__ ', ' Hobbies ', ' infoma ', ' tall ']

3, static method and instance method and class method are different, static method has no parameter limit, need neither instance parameter, nor need class parameter, use @staticmethod adorner when defining. Like similar methods, static methods can be accessed through class names or through instances.

class Person (object):

    tall = 180
    Hobbies = []
    def __init__ (self, Name, age,weight):
        self.name = name
        Self.age = age
        self.weight = weight
    @staticmethod    #静态方法装饰器
    def infoma ():     #没有参数限制, no instance arguments, Also use the class parameter
        print (Person.tall)
        print (person.hobbies)
#person. Infoma ()   #静态法可以通过类名访问
Bruce = Person ("Bruce", 25,180)   #通过实例访问

The main difference between the three methods is the parameter, the instance method is bound to an instance and can only be invoked through an instance, but for static methods and class methods, it can be invoked by both the class name and the instance.