Python Learning (II.)--about class

1, no permission control, before the class method or variable with "__" two underscores, then become "private" variable (actually through the _< class name >__< variable or method name > can be accessed)

2, the class of several automatic triggering of the built-in method:

• __new__ (cls[, ...]) The method returns an instance of this class, passing the passed parameters to the __init__ () method intact. This method is typically used when inheriting a class that is not modifiable, such as Str

Class Capstr (str):

Def __new__ (CLS, string):

string = String.upper ()

Return str.__new__ (CLS, String)

A = Capstr ("I Love You");

• __init__ (self[, ...]) The method is called the first time after the instance is created to initialize the object

Class Rectangle:

def __init__ (self, x, y):

self.x = X

Self.y = y

def getperi (self):

Return (self.x + self.y) * *

Aa=rectangle (3, 4);

Aa.getperi ()

• __del__ (self) //This method is triggered when the class instance is freed and finally garbage collected

C1=c ()

C2=c1

C3=c2

del C3//will not be triggered

Del C2//will not be triggered

Del C1//All references eliminated, triggering __del__

• __ADD__ (Self,other)//Two classes are added when a trigger
• __SUB__ (Self,other)//Two classes are subtracted when triggered
• __MUL__ (self,other)//Multiply Trigger
• __TRUEDIV__ (Self,other)//True Division

Python Learning (II.)--about class