🕷️ Crawler Inspector

/ 🐍 # Metaclasses In Python <https://realpython.com/python-metaclasses/> [python](https://codenote.mohsenjalali.ir/tag/python) Table of contents - [What is Metaclass?](https://codenote.mohsenjalali.ir/python/metaclass/#what-is-metaclass) - [Default metaclass in python is type and each custom metaclass should inherited from type.](https://codenote.mohsenjalali.ir/python/metaclass/#default-metaclass-in-python-is-type-and-each-custom-metaclass-should-inherited-from-type) # What is Metaclass? In python everythings are object and classes are also object. A metaclass in Python is a class of a class that defines how a class behaves. A class is itself an instance of a metaclass. In the below figure we can find how class definition occur.  ## Default metaclass in python is `type` and each custom metaclass should inherited from `type`. python Copy ``` class CustomMeta(type):@classmethoddef __prepare__(mcs, name, bases, **kwargs):namespace = super().__prepare__(name, bases)print(mcs,name,bases,namespace, kwargs)return namespacedef __new__(mcs, name, bases, namespace, **kwargs):cls = super().__new__(mcs, name, bases, namespace)print(cls,name,bases,namespace, kwargs)return clsdef __init__(cls, name, bases, namespace, **kwargs):print(cls,name,bases,namespace, kwargs)super().__init__(name, bases, namespace)class test(metaclass=CustomMeta):num= 10def is_available():return True ``` output Copy ``` <class '__main__.CustomMeta'> test () {} {}<class '__main__.test'> test () {'__module__': '__main__', '__qualname__': 'test', 'num': 10, 'is_available': <function test.is_available at 0x102ce3400>} {}<class '__main__.test'> test () {'__module__': '__main__', '__qualname__': 'test', 'num': 10, 'is_available': <function test.is_available at 0x102ce3400>} {} ``` [Edit this page](https://github.com/itsmohsenjalali/mohsencodenote/tree/master/code-notes/python/metaclass.md)  Hi Mohsen save your notes [All Notes](https://codenote.mohsenjalali.ir/) Tags [AWS](https://codenote.mohsenjalali.ir/tag/aws) [cleancode](https://codenote.mohsenjalali.ir/tag/cleancode) [Database](https://codenote.mohsenjalali.ir/tag/database) [design pattern](https://codenote.mohsenjalali.ir/tag/design-pattern) [Docker](https://codenote.mohsenjalali.ir/tag/docker) [Error](https://codenote.mohsenjalali.ir/tag/error) [Heroku](https://codenote.mohsenjalali.ir/tag/heroku) [Infrastructure](https://codenote.mohsenjalali.ir/tag/infrastructure) [Machine Learning](https://codenote.mohsenjalali.ir/tag/machine-learning) [Microservice](https://codenote.mohsenjalali.ir/tag/microservice) [MongoDB](https://codenote.mohsenjalali.ir/tag/mongo-db) [NestJS](https://codenote.mohsenjalali.ir/tag/nest-js) [nginx](https://codenote.mohsenjalali.ir/tag/nginx) [NodeJS](https://codenote.mohsenjalali.ir/tag/node-js) [Posgresql](https://codenote.mohsenjalali.ir/tag/posgresql) [Putty](https://codenote.mohsenjalali.ir/tag/putty) [python](https://codenote.mohsenjalali.ir/tag/python) [python package](https://codenote.mohsenjalali.ir/tag/python-package) [sever](https://codenote.mohsenjalali.ir/tag/sever)

In python everythings are object and classes are also object. A metaclass in Python is a class of a class that defines how a class behaves. A class is itself an instance of a metaclass. In the below figure we can find how class definition occur.  python ``` class CustomMeta(type):@classmethoddef __prepare__(mcs, name, bases, **kwargs):namespace = super().__prepare__(name, bases)print(mcs,name,bases,namespace, kwargs)return namespacedef __new__(mcs, name, bases, namespace, **kwargs):cls = super().__new__(mcs, name, bases, namespace)print(cls,name,bases,namespace, kwargs)return clsdef __init__(cls, name, bases, namespace, **kwargs):print(cls,name,bases,namespace, kwargs)super().__init__(name, bases, namespace)class test(metaclass=CustomMeta):num= 10def is_available():return True ``` output ``` <class '__main__.CustomMeta'> test () {} {}<class '__main__.test'> test () {'__module__': '__main__', '__qualname__': 'test', 'num': 10, 'is_available': <function test.is_available at 0x102ce3400>} {}<class '__main__.test'> test () {'__module__': '__main__', '__qualname__': 'test', 'num': 10, 'is_available': <function test.is_available at 0x102ce3400>} {} ```