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Query:

Response:

Calculated Shard: 116 (from laksa067)

2. Crawled Status Check

Query:

curl -X POST \
  'http://laksa116.int.ahrefs:8124/' \
  -H 'Content-Type: text/plain' \
  -H 'X-ClickHouse-Database: crawler3' \
  -H 'Authorization: Basic YXBpOg==' \
  -d 'SELECT getAhrefsURLFromUnparsed(src_unparsed) AS found_url, ifNull(toUnixTimestamp(download_stamp), 0) AS crawl_time, ifNull(toUnixTimestamp(props_url_first_seen), 0) AS first_indexed_time, download_http_code AS http_code, src_unparsed AS src_unparsed, src_root_hash AS src_root_hash, history_drop_reason AS history_drop_reason, meta_title AS meta_title, meta_descriptions AS meta_descriptions, attrs_boilerpipe_text AS attrs_boilerpipe_text, attrs_markdown AS attrs_markdown, attrs_readable_markdown AS attrs_readable_markdown, meta_canonical AS meta_canonical, ml_categories_json AS ml_categories_json, ml_types_json AS ml_types_json, ml_intent_types_json AS ml_intent_types_json, meta_language AS meta_language, attrs_author AS attrs_author, ifNull(toUnixTimestamp(attrs_publish_time), 0) AS attrs_publish_time, ifNull(toUnixTimestamp(attrs_original_publish_time), 0) AS attrs_original_publish_time, ifNull(attrs_is_republished, 0) AS attrs_is_republished, ifNull(attrs_nr_words, 0) AS attrs_nr_words, ifNull(attrs_boilerpipe_nr_words, 0) AS attrs_boilerpipe_nr_words, ifNull(body_ext_links_number, 0) AS body_ext_links_number, ifNull(body_int_links_number, 0) AS body_int_links_number, ifNull(meta_nofollow, 0) AS meta_nofollow, ifNull(meta_noarchive, 0) AS meta_noarchive, ifNull(props_was_rendered, 0) AS props_was_rendered, ifNull(src_redirect, \'\') AS src_redirect, ifNull(download_time_msec, 0) AS download_time_msec, ifNull(download_ttfb_msec, 0) AS download_ttfb_msec, ifNull(download_size, 0) AS download_size FROM crawler3.page_info_local FINAL PREWHERE (src_root_hash, src_unparsed) IN ((getAhrefsRootHashFromUnparsed(getAhrefsUnparsedNoserviceFromURL(\'https://python.pendancer.com/advanced/metaclasses.html\')), getAhrefsUnparsedNoserviceFromURL(\'https://python.pendancer.com/advanced/metaclasses.html\'))) FORMAT JSONEachRow'

Response:

{"found_url":"https:\/\/python.pendancer.com\/advanced\/metaclasses.html","crawl_time":1776519246,"first_indexed_time":1737184797,"http_code":200,"src_unparsed":"com,pendancer!python,\/advanced\/metaclasses.html s443","src_root_hash":"848193091939660316","history_drop_reason":null,"meta_title":"Metaclasses - Python","meta_descriptions":["Python course for the 90th Cyberspace Operations Squadron"],"attrs_boilerpipe_text":"Defined as “the class of a class”.\nAny class whose instances are themselves classes.\ntype is a metaclass for instance; it creates classes!\nUsed to construct classes. (always happens under hood)\nCan create dynamic classes with less lines using type.\nThink: instances are to classes as classes are to metaclasses.\nTo create a metaclass, create a class that inherits from type\n# in the most simple form\nclass Meta(type):\n    pass\nClasses are normally created with the type metaclass\nWe can create a class with a different metaclass:\n# Python 2\nclass Final(object):\n    __metaclass__ = Meta\n\u000B# Python 3\nclass Final(metaclass=Meta):\n    pass\n__new__():\nIt’s a method which is called before __init__(). It creates the object and return it.\n__init__():\nThis method just initialize the created object passed as parameter\nExample:\nclass Meta(type):\n    def __init__(cls, name, bases, dct):\n        print \"Creating class {} using Meta\".format(name)\n        super(Meta, cls).__init__(name, bases, dct)\n\u000Bclass Foo(object):\n    __metaclass__ = Meta\n\u000Bclass FooBar(Foo):\n    pass\nFirst we create a new metaclass called\nMeta\n:\nOn the construction of classes built using Meta, we print out that we are creating a class using Meta.\nNext, create a class called Foo… built from Meta rather than type.\nFinally, create a FooBar class from Foo.\nNotice how it too was built using Meta?\nEnd of Python Subject","attrs_markdown":"1. [Introduction](https:\/\/python.pendancer.com\/index.html)\n2. [**1\\.** C-4105L-TM Python Features](https:\/\/python.pendancer.com\/python_features\/index.html)\n3. 1. [**1\\.1.** Objectives](https:\/\/python.pendancer.com\/python_features\/objectives.html)\n   2. [**1\\.2.** Introduction to Python](https:\/\/python.pendancer.com\/python_features\/python_intro.html)\n   3. [**1\\.3.** PyDocs & PEP8](https:\/\/python.pendancer.com\/python_features\/pydocs_pep8.html)\n   4. [**1\\.4.** Objects](https:\/\/python.pendancer.com\/python_features\/objects.html)\n   5. 1. [**1\\.4.1.** Lab 1A](https:\/\/python.pendancer.com\/python_features\/lab1a.html)\n   6. [**1\\.5.** Py2 vs Py3 Differences](https:\/\/python.pendancer.com\/python_features\/py2_py3.html)\n   7. [**1\\.6.** Running Python](https:\/\/python.pendancer.com\/python_features\/running_python.html)\n4. [**2\\.** C-4110L-TM Python Variables and Data Types](https:\/\/python.pendancer.com\/Data_Types\/index.html)\n5. 1. [**2\\.1.** Objectives](https:\/\/python.pendancer.com\/Data_Types\/objectives.html)\n   2. [**2\\.2.** Variables](https:\/\/python.pendancer.com\/Data_Types\/variables.html)\n   3. 1. [**2\\.2.1.** Lab 2A](https:\/\/python.pendancer.com\/Data_Types\/lab2a.html)\n   4. [**2\\.3.** Numbers](https:\/\/python.pendancer.com\/Data_Types\/numbers.html)\n   5. 1. [**2\\.3.1.** Lab 2B & Lab2C](https:\/\/python.pendancer.com\/Data_Types\/lab2b_c.html)\n   6. [**2\\.4.** Strings](https:\/\/python.pendancer.com\/Data_Types\/strings.html)\n   7. 1. [**2\\.4.1.** Lab 2D & Lab2E](https:\/\/python.pendancer.com\/Data_Types\/lab2d_e.html)\n   8. [**2\\.5.** Lists](https:\/\/python.pendancer.com\/Data_Types\/lists.html)\n   9. 1. [**2\\.5.1.** Lab 2F](https:\/\/python.pendancer.com\/Data_Types\/lab2f.html)\n   10. [**2\\.6.** Bytes and Bytearray](https:\/\/python.pendancer.com\/Data_Types\/byte_array.html)\n   11. 1. [**2\\.6.1.** Lab 2G](https:\/\/python.pendancer.com\/Data_Types\/lab2g.html)\n   12. [**2\\.7.** Tuples, range & buffer](https:\/\/python.pendancer.com\/Data_Types\/tuples.html)\n   13. [**2\\.8.** Dictionaries & Sets](https:\/\/python.pendancer.com\/Data_Types\/mapping.html)\n   14. 1. [**2\\.8.1.** Lab 2H](https:\/\/python.pendancer.com\/Data_Types\/lab2h.html)\n6. [**3\\.** C-4115L-TM Python Operators and Flow Control](https:\/\/python.pendancer.com\/Flow_Control\/index.html)\n7. 1. [**3\\.1.** Objectives](https:\/\/python.pendancer.com\/Flow_Control\/objectives.html)\n   2. [**3\\.2.** Operators](https:\/\/python.pendancer.com\/Flow_Control\/operators.html)\n   3. [**3\\.3.** I\/O Print](https:\/\/python.pendancer.com\/Flow_Control\/io_print.html)\n   4. 1. [**3\\.3.1.** Lab 3A](https:\/\/python.pendancer.com\/Flow_Control\/lab3a.html)\n   5. [**3\\.4.** I\/O: Files](https:\/\/python.pendancer.com\/Flow_Control\/io_files.html)\n   6. 1. [**3\\.4.1.** Lab 3B](https:\/\/python.pendancer.com\/Flow_Control\/lab3b.html)\n   7. [**3\\.5.** If, Elif, Else](https:\/\/python.pendancer.com\/Flow_Control\/if_elif_else.html)\n   8. 1. [**3\\.5.1.** Lab 3C](https:\/\/python.pendancer.com\/Flow_Control\/lab3c.html)\n   9. [**3\\.6.** While Loops](https:\/\/python.pendancer.com\/Flow_Control\/while_loops.html)\n   10. 1. [**3\\.6.1.** Lab 3D](https:\/\/python.pendancer.com\/Flow_Control\/lab3d.html)\n   11. [**3\\.7.** For Loops](https:\/\/python.pendancer.com\/Flow_Control\/for_loops.html)\n   12. 1. [**3\\.7.1.** Lab 3E](https:\/\/python.pendancer.com\/Flow_Control\/lab3e.html)\n   13. [**3\\.8.** Break and Continue](https:\/\/python.pendancer.com\/Flow_Control\/break_continue.html)\n   14. 1. [**3\\.8.1.** Lab 3F](https:\/\/python.pendancer.com\/Flow_Control\/lab3f.html)\n8. [**4\\.** C-4120L-TM Python Functions](https:\/\/python.pendancer.com\/functions\/index.html)\n9. 1. [**4\\.1.** Objectives](https:\/\/python.pendancer.com\/functions\/objectives.html)\n   2. [**4\\.2.** Scope](https:\/\/python.pendancer.com\/functions\/scope.html)\n   3. [**4\\.3.** User Functions](https:\/\/python.pendancer.com\/functions\/user_functions.html)\n   4. [**4\\.4.** Lambda Functions](https:\/\/python.pendancer.com\/functions\/lambda_functions.html)\n   5. 1. [**4\\.4.1.** Lab 4A & 4B](https:\/\/python.pendancer.com\/functions\/lab4a.html)\n   6. [**4\\.5.** List Comprehension](https:\/\/python.pendancer.com\/functions\/list_comprehension.html)\n   7. [**4\\.6.** Recursion](https:\/\/python.pendancer.com\/functions\/recursion.html)\n   8. [**4\\.7.** Closures, Iterators & Generators](https:\/\/python.pendancer.com\/functions\/closures_iterators_generators.html)\n10. [**5\\.** C-4125L-TM Python Object Oriented Programming](https:\/\/python.pendancer.com\/oop\/index.html)\n11. 1. [**5\\.1.** Objectives](https:\/\/python.pendancer.com\/oop\/objectives.html)\n    2. [**5\\.2.** Modules](https:\/\/python.pendancer.com\/oop\/modules.html)\n    3. [**5\\.3.** Packages](https:\/\/python.pendancer.com\/oop\/packages.html)\n    4. 1. [**5\\.3.1.** Lab5A](https:\/\/python.pendancer.com\/oop\/lab5a.html)\n    5. [**5\\.4.** User Classes Pt1](https:\/\/python.pendancer.com\/oop\/user_classes.html)\n    6. 1. [**5\\.4.1.** Lab5B](https:\/\/python.pendancer.com\/oop\/lab5b.html)\n    7. [**5\\.5.** User Classes Pt2](https:\/\/python.pendancer.com\/oop\/user_classes_pt2.html)\n    8. 1. [**5\\.5.1.** Lab5C](https:\/\/python.pendancer.com\/oop\/lab5c.html)\n    9. [**5\\.6.** Exceptions](https:\/\/python.pendancer.com\/oop\/exceptions.html)\n    10. [**5\\.7.** OOP Principles](https:\/\/python.pendancer.com\/oop\/oop_principles.html)\n    11. [**5\\.8.** OOP Terminology Review \\[Bonus Lab\\]](https:\/\/python.pendancer.com\/oop\/oop_terminology.html)\n    12. 1. [**5\\.8.1.** Lab5D](https:\/\/python.pendancer.com\/oop\/lab5d.html)\n12. [**6\\.** C-4130L-TM Python Algorithms](https:\/\/python.pendancer.com\/Algorithms\/index.html)\n13. 1. [**6\\.1.** Objectives](https:\/\/python.pendancer.com\/Algorithms\/objectives.html)\n    2. [**6\\.2.** Algorithms Analysis](https:\/\/python.pendancer.com\/Algorithms\/Algorithm_Analysis.html)\n    3. [**6\\.3.** Algorithms Design](https:\/\/python.pendancer.com\/Algorithms\/Algorithm_Design.html)\n    4. [**6\\.4.** Big O Notation](https:\/\/python.pendancer.com\/Algorithms\/Big_O_notation.html)\n    5. [**6\\.5.** Big O Analysis](https:\/\/python.pendancer.com\/Algorithms\/Big_O_Analysis_Demos.html)\n    6. 1. [**6\\.5.1.** Lab 6A](https:\/\/python.pendancer.com\/Algorithms\/Big_0_Analysis_Perf_Labs.html)\n    7. [**6\\.6.** Searching Algorithms](https:\/\/python.pendancer.com\/Algorithms\/Searching_Algorithms.html)\n    8. [**6\\.7.** Sorting Algorithms](https:\/\/python.pendancer.com\/Algorithms\/Sort.html)\n14. [**7\\.** C-4130L-TM Python Data Structures](https:\/\/python.pendancer.com\/Data_Structures\/index.html)\n15. 1. [**7\\.1.** Objectives](https:\/\/python.pendancer.com\/Data_Structures\/objectives.html)\n    2. [**7\\.2.** List Pointer Structures](https:\/\/python.pendancer.com\/Data_Structures\/Lists_Pointer_Structures.html)\n    3. 1. [**7\\.2.1.** Singly Linked List](https:\/\/python.pendancer.com\/Data_Structures\/Singly_Linked_List.html)\n       2. [**7\\.2.2.** Doubly Linked List](https:\/\/python.pendancer.com\/Data_Structures\/Doubly_Linked_List.html)\n       3. [**7\\.2.3.** Linked List Demonstration](https:\/\/python.pendancer.com\/Data_Structures\/Linked_List_Demo.html)\n       4. [**7\\.2.4.** Lab 6B](https:\/\/python.pendancer.com\/Data_Structures\/Linked_List_Perf_Lab.html)\n       5. [**7\\.2.5.** Lab 6C](https:\/\/python.pendancer.com\/Data_Structures\/Singly_Linked_List_Lab.html)\n    4. [**7\\.3.** Stacks](https:\/\/python.pendancer.com\/Data_Structures\/Stacks_Lesson.html)\n    5. [**7\\.4.** Stacks Implementation](https:\/\/python.pendancer.com\/Data_Structures\/Stack_Implementation_Lesson.html)\n    6. [**7\\.5.** Queue](https:\/\/python.pendancer.com\/Data_Structures\/Queue_Lesson.html)\n    7. 1. [**7\\.5.1.** FIFO Queue](https:\/\/python.pendancer.com\/Data_Structures\/FIFO_Queue.html)\n       2. [**7\\.5.2.** Queue Demonstration 1](https:\/\/python.pendancer.com\/Data_Structures\/Queue_demo_lab.html)\n       3. [**7\\.5.3.** Queue Demonstration 2](https:\/\/python.pendancer.com\/Data_Structures\/Queue_Demo_lab_2.html)\n       4. [**7\\.5.4.** Lab 6D](https:\/\/python.pendancer.com\/Data_Structures\/Queue_Perf_Lab.html)\n    8. [**7\\.6.** Trees](https:\/\/python.pendancer.com\/Data_Structures\/Trees_Lesson.html)\n    9. 1. [**7\\.6.1.** Trees Example](https:\/\/python.pendancer.com\/Data_Structures\/Trees_Examples_Trees.html)\n       2. [**7\\.6.2.** Tree Led Demonstration](https:\/\/python.pendancer.com\/Data_Structures\/Tree_Led_Demos.html)\n       3. [**7\\.6.3.** Lab 6E](https:\/\/python.pendancer.com\/Data_Structures\/Trees_Perf_Labs.html)\n16. [**8\\.** C-4135L-TM Python Advanced Concepts](https:\/\/python.pendancer.com\/advanced\/index.html)\n17. 1. [**8\\.1.** Objectives](https:\/\/python.pendancer.com\/advanced\/objectives.html)\n    2. [**8\\.2.** CTypes and Structures](https:\/\/python.pendancer.com\/advanced\/ctypes.html)\n    3. [**8\\.3.** Regular Expressions](https:\/\/python.pendancer.com\/advanced\/regular_expressions.html)\n    4. [**8\\.4.** Additional Libraries and Modules](https:\/\/python.pendancer.com\/advanced\/additional_libraries_modules.html)\n    5. [**8\\.5.** Multithreading](https:\/\/python.pendancer.com\/advanced\/multithreading.html)\n    6. [**8\\.6.** UnitTesting](https:\/\/python.pendancer.com\/advanced\/unit_testing.html)\n    7. [**8\\.7.** Metaclasses](https:\/\/python.pendancer.com\/advanced\/metaclasses.html)\n    8. [**8\\.8.** Design Patterns](https:\/\/python.pendancer.com\/advanced\/designpatterns.html)\n    9. [**8\\.9.** Python Virtual Environment](https:\/\/python.pendancer.com\/advanced\/virtualenv.html)\n18. [C-4105L-TM Python Features - Part I](https:\/\/python.pendancer.com\/python_features\/part_i.html)\n19. [C-4110L-TM PythonVariables and Data Types - Part I](https:\/\/python.pendancer.com\/Data_Types\/part_i.html)\n20. [C-4115L-TM PythonOperators and Flow Control - Part I](https:\/\/python.pendancer.com\/Flow_Control\/part_i.html)\n21. [C-4120L-TM Python Functions - Part I](https:\/\/python.pendancer.com\/functions\/part_i.html)\n22. [C-4125L-TM Python Object Oriented Programming - Part I](https:\/\/python.pendancer.com\/oop\/part_i.html)\n23. [C-4130L-TM Python Algorithms - Part I](https:\/\/python.pendancer.com\/Algorithms\/part_i.html)\n24. [C-4130L-TM Python Data Structures - Part I](https:\/\/python.pendancer.com\/Data_Structures\/part_i.html)\n25. [C-4135L-TM Python Advanced Concepts - Part I](https:\/\/python.pendancer.com\/advanced\/part_i.html)\n\n- Light (default)\n- Rust\n- Coal\n- Navy\n- Ayu\n# Python\n\n# [Metaclasses](https:\/\/python.pendancer.com\/advanced\/metaclasses.html#metaclasses)\n![](https:\/\/python.pendancer.com\/assets\/QQ0OK.png)\n\n**Defined as “the class of a class”.**\n\n- Any class whose instances are themselves classes.\n- type is a metaclass for instance; it creates classes\\!\n- Used to construct classes. (always happens under hood)\n- Can create dynamic classes with less lines using type.\n- Think: instances are to classes as classes are to metaclasses.\n- To create a metaclass, create a class that inherits from type\n```\n# in the most simple form\nclass Meta(type):\n    pass\n```\n- Classes are normally created with the type metaclass\n- We can create a class with a different metaclass:\n```\n# Python 2\nclass Final(object):\n    __metaclass__ = Meta\n\u000B# Python 3\nclass Final(metaclass=Meta):\n    pass\n```\n**\\_\\_new\\_\\_():** It’s a method which is called before \\_\\_init\\_\\_(). It creates the object and return it.\n\n**\\_\\_init\\_\\_():** This method just initialize the created object passed as parameter\n\n**Example:**\n```\nclass Meta(type):\n    def __init__(cls, name, bases, dct):\n        print \"Creating class {} using Meta\".format(name)\n        super(Meta, cls).__init__(name, bases, dct)\n\u000Bclass Foo(object):\n    __metaclass__ = Meta\n\u000Bclass FooBar(Foo):\n    pass\n```\nFirst we create a new metaclass called **Meta**:\n\n- On the construction of classes built using Meta, we print out that we are creating a class using Meta.\n\nNext, create a class called Foo… built from Meta rather than type.\n\nFinally, create a FooBar class from Foo.\n\n- Notice how it too was built using Meta?\n***\n**End of Python Subject**","attrs_readable_markdown":null,"meta_canonical":null,"ml_categories_json":"","ml_types_json":"","ml_intent_types_json":"","meta_language":"en","attrs_author":null,"attrs_publish_time":0,"attrs_original_publish_time":1737184797,"attrs_is_republished":0,"attrs_nr_words":"600","attrs_boilerpipe_nr_words":"213","body_ext_links_number":0,"body_int_links_number":108,"meta_nofollow":0,"meta_noarchive":0,"props_was_rendered":0,"src_redirect":"","download_time_msec":484,"download_ttfb_msec":484,"download_size":5553}

3. Robots.txt Check

Query:

Response:

4. Spam/Ban Check

Query:

Response:

5. Seen Status Check

ℹ️ Skipped - page is already crawled

📄

INDEXABLE

✅

CRAWLED

6 days ago

🤖

ROBOTS ALLOWED

Page Info Filters

Filter	Status	Condition	Details
HTTP status	PASS	`download_http_code = 200`	HTTP 200
Age cutoff	PASS	`download_stamp > now() - 6 MONTH`	0.2 months ago
History drop	PASS	`isNull(history_drop_reason)`	No drop reason
Spam/ban	PASS	`fh_dont_index != 1 AND ml_spam_score = 0`	ml_spam_score=0
Canonical	PASS	`meta_canonical IS NULL OR = '' OR = src_unparsed`	Not set

Page Details

Property	Value
URL	https://python.pendancer.com/advanced/metaclasses.html
Last Crawled	2026-04-18 13:34:06 (6 days ago)
First Indexed	2025-01-18 07:19:57 (1 year ago)
HTTP Status Code	200
Content
Meta Title	Metaclasses - Python
Meta Description	Python course for the 90th Cyberspace Operations Squadron
Meta Canonical	null
Boilerpipe Text	Defined as “the class of a class”. Any class whose instances are themselves classes. type is a metaclass for instance; it creates classes! Used to construct classes. (always happens under hood) Can create dynamic classes with less lines using type. Think: instances are to classes as classes are to metaclasses. To create a metaclass, create a class that inherits from type # in the most simple form class Meta(type): pass Classes are normally created with the type metaclass We can create a class with a different metaclass: # Python 2 class Final(object): __metaclass__ = Meta # Python 3 class Final(metaclass=Meta): pass __new__(): It’s a method which is called before __init__(). It creates the object and return it. __init__(): This method just initialize the created object passed as parameter Example: class Meta(type): def __init__(cls, name, bases, dct): print "Creating class {} using Meta".format(name) super(Meta, cls).__init__(name, bases, dct) class Foo(object): __metaclass__ = Meta class FooBar(Foo): pass First we create a new metaclass called Meta : On the construction of classes built using Meta, we print out that we are creating a class using Meta. Next, create a class called Foo… built from Meta rather than type. Finally, create a FooBar class from Foo. Notice how it too was built using Meta? End of Python Subject
Markdown	1. [Introduction](https://python.pendancer.com/index.html) 2. [1\. C-4105L-TM Python Features](https://python.pendancer.com/python_features/index.html) 3. 1. [1\.1. Objectives](https://python.pendancer.com/python_features/objectives.html) 2. [1\.2. Introduction to Python](https://python.pendancer.com/python_features/python_intro.html) 3. [1\.3. PyDocs & PEP8](https://python.pendancer.com/python_features/pydocs_pep8.html) 4. [1\.4. Objects](https://python.pendancer.com/python_features/objects.html) 5. 1. [1\.4.1. Lab 1A](https://python.pendancer.com/python_features/lab1a.html) 6. [1\.5. Py2 vs Py3 Differences](https://python.pendancer.com/python_features/py2_py3.html) 7. [1\.6. Running Python](https://python.pendancer.com/python_features/running_python.html) 4. [2\. C-4110L-TM Python Variables and Data Types](https://python.pendancer.com/Data_Types/index.html) 5. 1. [2\.1. Objectives](https://python.pendancer.com/Data_Types/objectives.html) 2. [2\.2. Variables](https://python.pendancer.com/Data_Types/variables.html) 3. 1. [2\.2.1. Lab 2A](https://python.pendancer.com/Data_Types/lab2a.html) 4. [2\.3. Numbers](https://python.pendancer.com/Data_Types/numbers.html) 5. 1. [2\.3.1. Lab 2B & Lab2C](https://python.pendancer.com/Data_Types/lab2b_c.html) 6. [2\.4. Strings](https://python.pendancer.com/Data_Types/strings.html) 7. 1. [2\.4.1. Lab 2D & Lab2E](https://python.pendancer.com/Data_Types/lab2d_e.html) 8. [2\.5. Lists](https://python.pendancer.com/Data_Types/lists.html) 9. 1. [2\.5.1. Lab 2F](https://python.pendancer.com/Data_Types/lab2f.html) 10. [2\.6. Bytes and Bytearray](https://python.pendancer.com/Data_Types/byte_array.html) 11. 1. [2\.6.1. Lab 2G](https://python.pendancer.com/Data_Types/lab2g.html) 12. [2\.7. Tuples, range & buffer](https://python.pendancer.com/Data_Types/tuples.html) 13. [2\.8. Dictionaries & Sets](https://python.pendancer.com/Data_Types/mapping.html) 14. 1. [2\.8.1. Lab 2H](https://python.pendancer.com/Data_Types/lab2h.html) 6. [3\. C-4115L-TM Python Operators and Flow Control](https://python.pendancer.com/Flow_Control/index.html) 7. 1. [3\.1. Objectives](https://python.pendancer.com/Flow_Control/objectives.html) 2. [3\.2. Operators](https://python.pendancer.com/Flow_Control/operators.html) 3. [3\.3. I/O Print](https://python.pendancer.com/Flow_Control/io_print.html) 4. 1. [3\.3.1. Lab 3A](https://python.pendancer.com/Flow_Control/lab3a.html) 5. [3\.4. I/O: Files](https://python.pendancer.com/Flow_Control/io_files.html) 6. 1. [3\.4.1. Lab 3B](https://python.pendancer.com/Flow_Control/lab3b.html) 7. [3\.5. If, Elif, Else](https://python.pendancer.com/Flow_Control/if_elif_else.html) 8. 1. [3\.5.1. Lab 3C](https://python.pendancer.com/Flow_Control/lab3c.html) 9. [3\.6. While Loops](https://python.pendancer.com/Flow_Control/while_loops.html) 10. 1. [3\.6.1. Lab 3D](https://python.pendancer.com/Flow_Control/lab3d.html) 11. [3\.7. For Loops](https://python.pendancer.com/Flow_Control/for_loops.html) 12. 1. [3\.7.1. Lab 3E](https://python.pendancer.com/Flow_Control/lab3e.html) 13. [3\.8. Break and Continue](https://python.pendancer.com/Flow_Control/break_continue.html) 14. 1. [3\.8.1. Lab 3F](https://python.pendancer.com/Flow_Control/lab3f.html) 8. [4\. C-4120L-TM Python Functions](https://python.pendancer.com/functions/index.html) 9. 1. [4\.1. Objectives](https://python.pendancer.com/functions/objectives.html) 2. [4\.2. Scope](https://python.pendancer.com/functions/scope.html) 3. [4\.3. User Functions](https://python.pendancer.com/functions/user_functions.html) 4. [4\.4. Lambda Functions](https://python.pendancer.com/functions/lambda_functions.html) 5. 1. [4\.4.1. Lab 4A & 4B](https://python.pendancer.com/functions/lab4a.html) 6. [4\.5. List Comprehension](https://python.pendancer.com/functions/list_comprehension.html) 7. [4\.6. Recursion](https://python.pendancer.com/functions/recursion.html) 8. [4\.7. Closures, Iterators & Generators](https://python.pendancer.com/functions/closures_iterators_generators.html) 10. [5\. C-4125L-TM Python Object Oriented Programming](https://python.pendancer.com/oop/index.html) 11. 1. [5\.1. Objectives](https://python.pendancer.com/oop/objectives.html) 2. [5\.2. Modules](https://python.pendancer.com/oop/modules.html) 3. [5\.3. Packages](https://python.pendancer.com/oop/packages.html) 4. 1. [5\.3.1. Lab5A](https://python.pendancer.com/oop/lab5a.html) 5. [5\.4. User Classes Pt1](https://python.pendancer.com/oop/user_classes.html) 6. 1. [5\.4.1. Lab5B](https://python.pendancer.com/oop/lab5b.html) 7. [5\.5. User Classes Pt2](https://python.pendancer.com/oop/user_classes_pt2.html) 8. 1. [5\.5.1. Lab5C](https://python.pendancer.com/oop/lab5c.html) 9. [5\.6. Exceptions](https://python.pendancer.com/oop/exceptions.html) 10. [5\.7. OOP Principles](https://python.pendancer.com/oop/oop_principles.html) 11. [5\.8. OOP Terminology Review \[Bonus Lab\]](https://python.pendancer.com/oop/oop_terminology.html) 12. 1. [5\.8.1. Lab5D](https://python.pendancer.com/oop/lab5d.html) 12. [6\. C-4130L-TM Python Algorithms](https://python.pendancer.com/Algorithms/index.html) 13. 1. [6\.1. Objectives](https://python.pendancer.com/Algorithms/objectives.html) 2. [6\.2. Algorithms Analysis](https://python.pendancer.com/Algorithms/Algorithm_Analysis.html) 3. [6\.3. Algorithms Design](https://python.pendancer.com/Algorithms/Algorithm_Design.html) 4. [6\.4. Big O Notation](https://python.pendancer.com/Algorithms/Big_O_notation.html) 5. [6\.5. Big O Analysis](https://python.pendancer.com/Algorithms/Big_O_Analysis_Demos.html) 6. 1. [6\.5.1. Lab 6A](https://python.pendancer.com/Algorithms/Big_0_Analysis_Perf_Labs.html) 7. [6\.6. Searching Algorithms](https://python.pendancer.com/Algorithms/Searching_Algorithms.html) 8. [6\.7. Sorting Algorithms](https://python.pendancer.com/Algorithms/Sort.html) 14. [7\. C-4130L-TM Python Data Structures](https://python.pendancer.com/Data_Structures/index.html) 15. 1. [7\.1. Objectives](https://python.pendancer.com/Data_Structures/objectives.html) 2. [7\.2. List Pointer Structures](https://python.pendancer.com/Data_Structures/Lists_Pointer_Structures.html) 3. 1. [7\.2.1. Singly Linked List](https://python.pendancer.com/Data_Structures/Singly_Linked_List.html) 2. [7\.2.2. Doubly Linked List](https://python.pendancer.com/Data_Structures/Doubly_Linked_List.html) 3. [7\.2.3. Linked List Demonstration](https://python.pendancer.com/Data_Structures/Linked_List_Demo.html) 4. [7\.2.4. Lab 6B](https://python.pendancer.com/Data_Structures/Linked_List_Perf_Lab.html) 5. [7\.2.5. Lab 6C](https://python.pendancer.com/Data_Structures/Singly_Linked_List_Lab.html) 4. [7\.3. Stacks](https://python.pendancer.com/Data_Structures/Stacks_Lesson.html) 5. [7\.4. Stacks Implementation](https://python.pendancer.com/Data_Structures/Stack_Implementation_Lesson.html) 6. [7\.5. Queue](https://python.pendancer.com/Data_Structures/Queue_Lesson.html) 7. 1. [7\.5.1. FIFO Queue](https://python.pendancer.com/Data_Structures/FIFO_Queue.html) 2. [7\.5.2. Queue Demonstration 1](https://python.pendancer.com/Data_Structures/Queue_demo_lab.html) 3. [7\.5.3. Queue Demonstration 2](https://python.pendancer.com/Data_Structures/Queue_Demo_lab_2.html) 4. [7\.5.4. Lab 6D](https://python.pendancer.com/Data_Structures/Queue_Perf_Lab.html) 8. [7\.6. Trees](https://python.pendancer.com/Data_Structures/Trees_Lesson.html) 9. 1. [7\.6.1. Trees Example](https://python.pendancer.com/Data_Structures/Trees_Examples_Trees.html) 2. [7\.6.2. Tree Led Demonstration](https://python.pendancer.com/Data_Structures/Tree_Led_Demos.html) 3. [7\.6.3. Lab 6E](https://python.pendancer.com/Data_Structures/Trees_Perf_Labs.html) 16. [8\. C-4135L-TM Python Advanced Concepts](https://python.pendancer.com/advanced/index.html) 17. 1. [8\.1. Objectives](https://python.pendancer.com/advanced/objectives.html) 2. [8\.2. CTypes and Structures](https://python.pendancer.com/advanced/ctypes.html) 3. [8\.3. Regular Expressions](https://python.pendancer.com/advanced/regular_expressions.html) 4. [8\.4. Additional Libraries and Modules](https://python.pendancer.com/advanced/additional_libraries_modules.html) 5. [8\.5. Multithreading](https://python.pendancer.com/advanced/multithreading.html) 6. [8\.6. UnitTesting](https://python.pendancer.com/advanced/unit_testing.html) 7. [8\.7. Metaclasses](https://python.pendancer.com/advanced/metaclasses.html) 8. [8\.8. Design Patterns](https://python.pendancer.com/advanced/designpatterns.html) 9. [8\.9. Python Virtual Environment](https://python.pendancer.com/advanced/virtualenv.html) 18. [C-4105L-TM Python Features - Part I](https://python.pendancer.com/python_features/part_i.html) 19. [C-4110L-TM PythonVariables and Data Types - Part I](https://python.pendancer.com/Data_Types/part_i.html) 20. [C-4115L-TM PythonOperators and Flow Control - Part I](https://python.pendancer.com/Flow_Control/part_i.html) 21. [C-4120L-TM Python Functions - Part I](https://python.pendancer.com/functions/part_i.html) 22. [C-4125L-TM Python Object Oriented Programming - Part I](https://python.pendancer.com/oop/part_i.html) 23. [C-4130L-TM Python Algorithms - Part I](https://python.pendancer.com/Algorithms/part_i.html) 24. [C-4130L-TM Python Data Structures - Part I](https://python.pendancer.com/Data_Structures/part_i.html) 25. [C-4135L-TM Python Advanced Concepts - Part I](https://python.pendancer.com/advanced/part_i.html) - Light (default) - Rust - Coal - Navy - Ayu # Python # [Metaclasses](https://python.pendancer.com/advanced/metaclasses.html#metaclasses) ![](https://python.pendancer.com/assets/QQ0OK.png) Defined as “the class of a class”. - Any class whose instances are themselves classes. - type is a metaclass for instance; it creates classes\! - Used to construct classes. (always happens under hood) - Can create dynamic classes with less lines using type. - Think: instances are to classes as classes are to metaclasses. - To create a metaclass, create a class that inherits from type ``` # in the most simple form class Meta(type): pass ``` - Classes are normally created with the type metaclass - We can create a class with a different metaclass: ``` # Python 2 class Final(object): __metaclass__ = Meta # Python 3 class Final(metaclass=Meta): pass ``` \_\_new\_\_(): It’s a method which is called before \_\_init\_\_(). It creates the object and return it. \_\_init\_\_(): This method just initialize the created object passed as parameter Example: ``` class Meta(type): def __init__(cls, name, bases, dct): print "Creating class {} using Meta".format(name) super(Meta, cls).__init__(name, bases, dct) class Foo(object): __metaclass__ = Meta class FooBar(Foo): pass ``` First we create a new metaclass called Meta: - On the construction of classes built using Meta, we print out that we are creating a class using Meta. Next, create a class called Foo… built from Meta rather than type. Finally, create a FooBar class from Foo. - Notice how it too was built using Meta? * End of Python Subject**
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