Python meta-classes and custom meta-classes

1: Meta-class

Meta class: The creation and management of classes

The meta class of all classes is type

class A:    　　 Pass Print (Type (a))　　

Results: <class ' type ' >

2: Custom meta-class

Instantiation of a class: (See the basics and essentials of a Class)

1) Call __new__ () to create an instance

2) call __init__ () to initialize the instance created above

So: Customizing the instance is changing the parent class's __new__ () or __init__ () method

Example:

1 classMymeta (type):2     def __init__(self,name,bases,dicts):3         Print('Init Instance.')4 5     def __new__(cls,name,bases,dicts):6dicts['Info'] =LambdaSelfPrint('DJX.')#Append instance method info ()7res = type.__new__(cls,name,bases,dicts)#invoke the new method of the parent class type to instantiate the instance8Res.company ='Maizi'                       #Append Property9         returnRes#Returning InstancesTen  One classCustom (Metaclass=mymeta):#Use the keyword to indicate that the meta-class is not type but Mymeta A     Pass -  - if __name__=='__main__': thecus =Custom () - Cus.info () -     Print(Cus.company) -  +  - #the writing of python2.x + #class Cus: A  #__metaclass__ = Mymeta at   #Pass

Operation Result:

Init Instance.
Djx.
Maizi

Python meta-classes and custom meta-classes