Python base Classes and objects

Concepts of classes and objects

Class is the most important concept of object-oriented design, which is the combination of feature and skill, while class is a combination of features and skills with similar objects.

• In the real world: there must be objects first, then there are classes
• In the program: Be sure to define the class first, then produce the object

在Python中程序中的类用class关键字定义，而在程序中特征用变量标识，技能用函数标识，因而类中最常见的无非是：变量和函数的定义

　　

ClassStudent: School=' xxxxx 'DefLearn(Selfprint ( ' is learning ' ) def eatprint ( ' is eating ' ) def sleep (Selfprint  ' is sleeping ' ) 
    

Attention:

• The class can have arbitrary Python code that executes during the class definition phase, resulting in a new namespace that holds the class's variable name and function name, which can be viewed through student.__dict__
• The name defined in the class is the property of the class, and the point is the syntax for accessing the property.
• For the classic class we can manipulate the name of the class namespace through the dictionary, but the new class has limitations

Use of the class

• Referencing the properties of a class

OldboyStudent.school #查OldboyStudent.school=‘Oldboy‘ #改OldboyStudent.x=1 #增del OldboyStudent.x #删

• Call the class, or instantiate it, to get the object in the program

s1=Student()s2=Student()s3=Student()如此，s1、s2、s3都一样了，而这三者除了相似的属性之外还各种不同的属性，这就用到了__init__

• __Init__ Method

This method is executed after the object has been generated, only to initialize the object, can have arbitrary code, but must not have a return valueClassOldboystudent:......Def__init__(Self, name, age, sex.name< Span class= "token operator" >=name self.age=age self< Span class= "token punctuation" >.sex=sex ..s1=student (, ' man ' ,28) # Call the class first to produce the empty object S1, and then call student.__init__ (S1, ' rain ', ' Male ', ') 
         

s2=oldboystudent  ' southernmost ' , ' female ' Span class= "token punctuation" >,38)   

 < Span class= "token punctuation" >       

Use of objects

The namespace of the object can be viewed with s2.__dict__, viewing the result as{' Name ':' Southernmost ' ' age ' :  ' sex ' 38}s2.name = ' Wang San '  change, equivalent to s2.__dict__[ ' Name ']= ' Wang San ' s2.course= ' Python ' del s2.course  Delete, equivalent to S2.__dict__.pop (' course ')    

< Span class= "token punctuation" > < Span class= "token punctuation" > 
 
           

　　

Python base Classes and objects