Where is the Python documentation for the special methods? (init, new, len, ...)

Question

Where is a complete list of the special double-underscore/dunder methods that can be used in classes? (e.g., __init__, __new__, __len__, __add__)

@Mk12: tags are about questions not about askers. Please, stop reverting — SilentGhost, Sep 14 '09 at 18:16
I'm trying to figure out what the question means. These these are well-covered in the Python documentation. Since these things are well-documented, I'm trying to understand what the question means. — S.Lott, Jan 23 '12 at 03:46

Martin Geisler · Accepted Answer · 2009-09-14T17:54:00.290

65

Please take a look at the special method names section in the Python language reference.

edited Sep 14 '09 at 17:54

answered Sep 13 '09 at 21:05

Martin Geisler

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Justin · Answer 2 · 2016-05-11T20:35:13.757

If, like me, you want a plain, unadorned list, here it is. I compiled it based on the Python documentation link from the accepted answer.

__abs__
__add__
__and__
__call__
__class__
__cmp__
__coerce__
__complex__
__contains__
__del__
__delattr__
__delete__
__delitem__
__delslice__
__dict__
__div__
__divmod__
__eq__
__float__
__floordiv__
__ge__
__get__
__getattr__
__getattribute__
__getitem__
__getslice__
__gt__
__hash__
__hex__
__iadd__
__iand__
__idiv__
__ifloordiv__
__ilshift__
__imod__
__imul__
__index__
__init__
__instancecheck__
__int__
__invert__
__ior__
__ipow__
__irshift__
__isub__
__iter__
__itruediv__
__ixor__
__le__
__len__
__long__
__lshift__
__lt__
__metaclass__
__mod__
__mro__
__mul__
__ne__
__neg__
__new__
__nonzero__
__oct__
__or__
__pos__
__pow__
__radd__
__rand__
__rcmp__
__rdiv__
__rdivmod__
__repr__
__reversed__
__rfloordiv__
__rlshift__
__rmod__
__rmul__
__ror__
__rpow__
__rrshift__
__rshift__
__rsub__
__rtruediv__
__rxor__
__set__
__setattr__
__setitem__
__setslice__
__slots__
__str__
__sub__
__subclasscheck__
__truediv__
__unicode__
__weakref__
__xor__

Actually, some of those--like `__dict__`--are not methods. – Braden Best Aug 26 '18 at 15:39 — Braden Best, Aug 26 '18 at 15:39

score 13 · Answer 3 · edited Aug 06 '12 at 04:42

13

Dive Into Python has an excellent appendix for them.

edited Aug 06 '12 at 04:42

Don Kirkby

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answered Sep 13 '09 at 21:11

Jonny Buchanan

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score 7 · Answer 4 · answered Sep 13 '09 at 21:06

7

Here is a complete reference of all the Python magic methods.

answered Sep 13 '09 at 21:06

e-satis

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score 5 · Answer 5 · answered Jun 16 '16 at 05:03

5

Do this if you prefer reading documentation from a CLI instead of the browser.

$ pydoc SPECIALMETHODS

answered Jun 16 '16 at 05:03

IcarianComplex

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score 4 · Answer 6 · answered Sep 13 '09 at 21:16

4

See Python Quick reference

answered Sep 13 '09 at 21:16

Elazar Leibovich

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score 3 · Answer 7 · edited May 29 '18 at 19:28

3

For somebody who is relatively new to Python, and for whom the documentation is often not quite accessible enough (like myself): somebody wrote a nice introduction with lots of examples on how the special (magic) methods work, how to use them, etc.

edited May 29 '18 at 19:28

George Stocker

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answered Sep 06 '13 at 15:16

Stefan van den Akker

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score 0 · Answer 8 · answered Sep 03 '17 at 22:47

Python's double underscore ("dunder") methods are also known as datamodel methods because they are at the core of Python's data model, providing a protocol for customizing (overloading) built-in methods. This is the reason why they are listed in the "Data Model" section of the Python's documentation.

score -3 · Answer 9 · answered Sep 13 '09 at 21:49

-3

Familiarize yourself with the dir function.

answered Sep 13 '09 at 21:49

TheOne

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1

but that would only do what I wanted if a the class passed to it implemented all of the special methods. – mk12 Sep 13 '09 at 22:55

Where is the Python documentation for the special methods? (init, new, len, ...)

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Where is the Python documentation for the special methods? (__init__, __new__, __len__, ...)

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Where is the Python documentation for the special methods? (init, new, len, ...)