How to override the [] operator in Python?

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Chapters
00:00 Question
00:22 Accepted answer (Score 420)
00:48 Answer 2 (Score 82)
01:20 Answer 3 (Score 22)
01:36 Thank you

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Full question
https://stackoverflow.com/questions/1957...

Accepted answer links:
[__getitem__]: https://docs.python.org/reference/datamo...
[__setitem__]: https://docs.python.org/reference/datamo...

Answer 2 links:
http://docs.python.org/reference/datamod...

Answer 3 links:
http://docs.python.org/reference/datamod...

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https://meta.stackexchange.com/help/lice...

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Tags
#python #operatoroverloading

#avk47

ACCEPTED ANSWER

Score 457

You need to use the __getitem__ method.

class MyClass:
    def __getitem__(self, key):
        return key * 2

myobj = MyClass()
myobj[3] #Output: 6

And if you're going to be setting values you'll need to implement the __setitem__ method too, otherwise this will happen:

>>> myobj[5] = 1
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: MyClass instance has no attribute '__setitem__'

ANSWER 2

Score 90

To fully overload it you also need to implement the __setitem__and __delitem__ methods.

edit

I almost forgot... if you want to completely emulate a list, you also need __getslice__, __setslice__ and __delslice__.

There are all documented in http://docs.python.org/reference/datamodel.html

ANSWER 3

Score 24

You are looking for the __getitem__ method. See http://docs.python.org/reference/datamodel.html, section 3.4.6