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如何在Python中覆盖[]运算符？

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问题：如何在Python中覆盖[]运算符？
回答 0
回答 1
回答 2

问题：如何在Python中覆盖[]运算符？

覆盖[]Python中的类的运算符（下标表示法）的方法名称是什么？

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What is the name of the method to override the [] operator (subscript notation) for a class in Python?

回答 0

您需要使用__getitem__方法。

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

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

如果要设置值，则也需要实现该__setitem__方法，否则会发生这种情况：

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

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__'

回答 1

要完全重载它，您还需要实现__setitem__和__delitem__方法。

编辑

我差点忘了…如果您想完全模仿一个列表，则还需要__getslice__, __setslice__ and __delslice__。

所有内容都记录在http://docs.python.org/reference/datamodel.html中

点击查看英文原文

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

回答 2

您正在寻找__getitem__方法。参见http://docs.python.org/reference/datamodel.html第3.4.6节

点击查看英文原文

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