Classes in Python

Classes in Python
Content Overview
Concepts of the class:
A class is an abstract set of methods and properties.
Property
instance variables (in each instance memory)
class variables (in-class memory)
Private attribute __var
Method
Construction method
destructor (the default is, the code is empty and the write is equivalent to refactoring it)
Other methods

Object: An instance of a class (an object that is obtained after instantiating a class)
Properties of the class:
Packaging:
The implementation details of some functions are not exposed to external
Inherited:
Inheritance order: (Overwrite, re-inherit, add again)
Inheritance: Code Reuse
How to Inherit:
Single inheritance
Multiple inheritance
2.7 Classic class Depth first
New class Breadth First
3.x all Breadth First
Polymorphic:
Interface reuse (one interface, multiple implementations)

---

1 Create a class:
------

Class keyword, Schoolmember class name (object) New class notation
Class Schoolmember (object):
member = 0 #类变量
def __init__ (self,name,age,sex):
Self.name = Name #实例属性
Self.age = Age
Self.__sex = Sex #定义私有属性
Self.register ()

def print_info (self):
Print ("---info%s start------"%self.name)
For k,v in Self.__dict__.items ():
Print ("\ T", k,v)
Print ("---info%s end------"% self.name)

def print_sex (self):
Print ("%s is%s"% (Self.name,self.__sex))
def register (self):
Schoolmember.member +=1
Print ("Now the member is%s"% schoolmember.member)

def __del__ (self):
"Destructor"
Print ("Del the%s"%self.name)
Schoolmember.member-=1
Print ("Now the member is%s"% schoolmember.member)

T1 = Teacher (' AA ', ' a ', ' M ', ', ' py ') #生成对象
T1.print_sex () #私有属性在类外部无法直接进行访问, can only be accessed through the class method.

Properties of the class:
-----

1. Package:
---

Encapsulation is an abstraction of a specific object that is hidden from the outside of the program, meaning that other programs cannot invoke it.

2. Inheritance:
---

2.1. Single Inheritance
Class Animal:
def __init__ (Self,name,voice=none): # Voice initialization defaults to None
Self.name = Name
Self.voice = Voice
def Say (self):
Print (Self.voice)
def Run (self):
Pass # NULL Action statement (no action)

Class Cdog (Animal): # Inherit class Animal
# def __init__ (Self,name,voice):
# super (Cdog,self) __init__ (Name,voice)
def setvoice (Self,voice): # Subclass Add Function Setvoice
Self.voice = Voice
def run (self): # Subclass overloaded Function Run
Print (' Running ')

Bobo = Cdog (' ala ')
Bobo. Setvoice (' Wang ')
Bobo. Say ()

2.2, more inherit the new class:
Class A (object):
def __init__ (self):
Pass
def f (self):
Print (' A ')

Class B (A):
def __init__ (self):
Pass
# def F (self):
# print (' B ')

Class C (A):
def __init__ (self):
Pass
def f (self):
Print (' C ')

Class D (B,C):
def __init__ (self):
Super (D, self). __init__ ()
# def F (self):
# print (' D ')

c = D ()
C.F ()
Print (d.__mro__)

Output information:
C
(<class ' __main__. D ';, <class ' __main__. B ';, <class ' __main__. C ';, <class ' __main__. A ';, <class ' object ' >)

The inheritance way of the new class: Breadth First, inherit the way of first left and right.
The multiple-inheritance approach of version 3.6 is breadth-first.
The 2.7 version of the new poetry succession is also the principle of breadth first.

Classic-Class Way:
Class A:
def __init__ (self):
Pass
def f (self):
Print (' A ')

Class B (A):
def __init__ (self):
Pass
# def F (self):
# print (' B ')

Class C (A):
def __init__ (self):
Pass
def f (self):
Print (' C ')

Class D (B,C):
def __init__ (self):
#super (D, self). __init__ ()
B.__init__ (self)
C.__init__ (self)
# def F (self):
# print (' D ')

c = D ()
C.F ()
#print (d.__mro__)

2.7 Version output A, the classic class is depth first.
3.6 version Output C, breadth First principle

Classes in Python