在Python中创建两个具有相同值的不可变对象 [英] Create two immutable objects with the same value in Python

问题描述

在Python中是否可以创建两个具有相同值的不可变对象?

Is it possible in Python to create two immutable objects with the same value?

为使您理解我的意思，下面是一些示例:

So that you understand what I mean, here are some examples:

>>> a = 13
>>> b = 13
>>> a is b
True


>>> a = 13
>>> b = 26/2
>>> a is b
True


>>> a = 13
>>> b = int.__new__(int, 13)
>>> a is b
True


>>> a = 13
>>> b = int("13")
>>> a is b
True

是否可以用相同的值创建a和b，但a is b返回False? 只是学习....:D

Is it possible to create a and b with the same value but a is b to return False? Just learning.... :D

推荐答案

当然，只需选择一个太大而无法缓存的值即可.

Sure, just choose a value that is too large to be cached:

>>> a = 256
>>> b = 256
>>> a is b
True
>>> a = 257
>>> b = 257
>>> a is b
False
>>> a = "hey"
>>> b = "hey"
>>> a is b
True
>>> a = "hey!"
>>> b = "hey!"
>>> a is b
False

将仅缓存小整数和短字符串(这是与实现有关的，因此无论如何您都不应依赖它). is只能用于测试对象 identity ，而不能用于测试 quality .

Only small integers and short strings will be cached (and this is implementation-dependent, so you shouldn't rely on that anyway). is should only be used for testing object identity, never for testing equality.

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