Python in Meta class

A. Premises:

In Python everything is an object, either a class object or a meta-class object, and the type meta-class is its own object. An inheritance hierarchy is represented as a type (meta-Class)--Class (built-in and user-defined) and an instance of the class.

Two. Purpose:

When you create a class, you automatically change the class, in other words, create something like this.

Three. __metaclass__

You can create a class by specifying __metaclass__ to use a user-defined meta-class.

　　Class Statement parsing order :

Class Myclass (object): Pass

MyClass inside of __metaclass__----__metaclass__ in the parent class (object)---The default type in the module

Four. How to use:

1.__metaclass__ = Callablefunc

1 def   Callablefunc (classname, Bases, DCT):2         ... 3         Data Processing 4         ... 5         return  Type (classname, bases, NEWDCT)

2 __metaclass__ = Custom meta-Class

1 class Mymeta (type): 2         def __new__ (CLS, classname, Bases, DCT): 3                 ... 4                 Data processing for DCT, generating NEWDCT5                 ... 6                 return super (MYMETA,CLS). __new__ (CLS,CLASSNAME,BASES,NEWDCT)

　　

　　　

　　

Python in Meta class