问题与“最小惊讶”和可变默认参数不同。

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我运行这样的代码：

def funtest(L=[]):
    L.append(L)
    return L
print(funtest([2]))
print(funtest([3]))
print(funtest([4]))

实际输出在下面。

[2, [...]]
[3, [...]]
[4, [...]]

I know a very heated discussion about the Mutable Default Arguments in before: Least Astonishment” and the Mutable Default Argument

根据Mutable Default Arguments规则，我认为输出应为：

[2, [...]]
[2,3, [...]]
[2,3,4, [...]]

有人对此有想法吗？谢谢

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lenim
lenim

当您不向函数传递任何参数时，默认参数就会出现

here you are passing arguments to the function namely [2], [3] and [4] and hence default value is not being used

in your question you mention that for first print output should be [2, [...]] if you are able to understand that , then next ones are exactly same as default argument never comes in the picture.. just focus on how [2, [...]] came

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