Oldboy 21th Day. I Love Python. Object-oriented encapsulation, polymorphism, inheritance three major features

First, the main content:
Interface class: ( Only in the work, writing a specification.)

Abstract class:
Usefulness: At work, if you prescribe several classes, you must have the same method, if you are abstract class.

Packaging:
1, put some properties or methods (some useful information) in a space.

2, Private member encapsulation: private static variable, private property, Private method feature: +__ double underline before variable, and outside class, subclass accesses private variable, private method is inaccessible. Because the private member, at run time, will become: _ Class name __ variable name so you are outside of the class, or the derived class is inaccessible.
Some methods, variables, properties, are used only within the class, are not allowed outside of the class, or are called in a derived class.

The overall classification of the class:
The first part:
public static fields
private static fields
Part II:
Special method: __INIT__,__STR__, etc.
Common methods:
Private methods:
Class method:
Property:

Oldboy 21th Day. I Love Python. Object-oriented encapsulation, polymorphism, inheritance three major features