isinstance（x，list）当迭代包含字符串和列表的列表时 [英] isinstance(x, list) when iterating a list containing strings and lists

问题描述

在迭代嵌套列表自内向外中，我被告知类型检查不是Pythonic。一般来说，这是真的：我们只想看界面（鸭子类型），而不是一个特定的类型。

At Iterating nested list inside-out, I was told that "type-checking isn't Pythonic". Generally, this is true: we want to look only at the interface (duck-typing) rather than a specific type.

问题询问窗体的嵌套列表 ['a'，['c'，['e']，'d']，'b'] ，我们特别考虑字符串原子（不可迭代）。所以，我们不能使用毯子 collections.Iterable ，但另一方面 isinstance（x，list）

The question asks about nested lists of the form ['a', ['c', ['e'], 'd'], 'b'], and we specifically consider strings atomic (non-iterable). So, we can't use a blanket collections.Iterable, but on the other hand isinstance(x, list) does seem a bit hacky.

我的回答是

def traverse(l):
    for x in l:
        if isinstance(x, list):
            traverse(x)
    callback(l)

什么是更好的方法？或者 isinstance 确定这里？

What's a better approach? Or is isinstance OK here?

推荐答案

确定这里 - 虽然我可以更改为

I think that your answer is OK here -- Although I might change it to

if not isinstance(x,basestring):
   ...

以根据预期的输入更多地接受。最终，你需要的一些问题 isinstance 这就是为什么它仍然存在于语言。

to make it a little more accepting depending on the expected input. Ultimately, some problems you need isinstance which is why it still exists in the language.

话虽如此，关于这个问题，非pythonic的事情是数据结构。在python中，如果一个问题看起来很难，这可能意味着你以错误的方式存储数据...（当然，我意识到你不能控制其他问题的数据结构的原始海报是什么; - ）。

That being said, the thing about this problem that is un-pythonic is the data-structure. In python, if a problem seems really hard, it probably means you're storing the data in the wrong way ... (Of course, I realize that you had no control over what the original poster of the other question's data structure was ;-).

基本上，我想我的观点是 isinstance 是 hack 你需要做柠檬水，当你的同事/一些图书馆作家在某处给你柠檬 - 否则你尽可能避免它。

Basically, I guess that my view is that isinstance is the hack that you need to make lemonade when your colleagues/some library writer somewhere gives you lemons -- Otherwise you avoid it where possible.

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