The path to Python, 18th: Introduction to Python and Basics 18

Python3 Object-Oriented Programming 2

Class method:

@classmethod

Function: 1, class method is the only way to access class variables;

2, the class method needs to use the @classmethod adorner definition;

3, the first parameter of a class method is an instance of the class, and the Convention is written as CLS

Note: 1, class instances and object instances can call class methods;

2, class methods cannot be method instance variables

Comparison of class methods and instance methods:

1, the class method can access the class variable, cannot access the instance variable;

Instance methods can access class variables and also access instance variables

2, the class method can be invoked with an instance, or it can be invoked with a class;

The instance method must pass in the instance when it is called;

1 classBank:2Moneys = 10000000#10 million3 @classmethod4     defTotal_money (CLS):5         Print("Total capital of a bank:", Cls.moneys)6 7     def __init__(self, b):8Self.branch =b9Self.moneys = 5000000TenSelf.__class__. Moneys-= 5000000 One  A  -Bank.total_money ()#Total capital of a bank: 10000000 -B1 = Bank ("XXX Address sub-branch") theB1.total_money ()#Total capital of a bank: 5000000

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Static methods

@staticmethod

Function: 1, static method is a normal function;

2, the static method is defined inside the class and can only be called by virtue of that class and instance

3, static methods need to be defined using the @staticmethod adorner

4, the static method is the same as the normal function definition, does not need to pass in the self instance parameter and the CLS class parameter;

Description: 1, both class instances and object instances can call static methods;

2, static methods can not method class variables and instance variables;

The path to Python, 18th: Introduction to Python and Basics 18