多维类列表-覆盖问题 [英] Multidimensional list of classes - overwriting issue

问题描述

我想创建一个类列表，但是每次更改列表中的一个元素时，列表中的所有类元素都会被覆盖:

I want to create a list of classes, but every time I change an element in the list, all class elements in the list are overwritten:

class TypeTest:
    def __init__(self):
    self.val = int()

data = list([TypeTest for _ in range(3)])

for i in range(3):
    data[i].val = i
    print([data[0].val, data[1].val, data[2].val])

最后，我需要一个多维数组，并且将有一个更复杂的类，但是问题是相同的.

At the end, I need a multidimensional array and will have a more complex class, but the issue is the same.

推荐答案

TypeTest 是一种类型； TypeTest()创建该类型的实例.您需要

TypeTest is a type; TypeTest() creates an instance of that type. You need

data = list([TypeTest() for _ in range(3)])

代替

data = list([TypeTest for _ in range(3)])

在后一种情况下，您只是将同一 TypeTest 的多个副本添加到列表中.

In the latter case, you are just adding multiple copies of the same TypeTest to the list.

实际上，如果打印列表元素的内存地址，则会发现它们是同一对象:

Indeed, if you print the memory address of your list elements, you will find that they're the same object:

>>> data = list([TypeTest for _ in range(3)])
>>> print([id(x) for x in data])
[140184769568224, 140184769568224, 140184769568224]

而

>>> data = list([TypeTest() for _ in range(3)])
>>> print([id(x) for x in data])
[4451998096, 4451996816, 4451996176]

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