python __all__模块级别变量有什么用? [英] What's the python __all__ module level variable for?

问题描述

我已经在python/Lib源代码中看到了很多，但是我不知道它是干什么的.

I've seen it a lot in python/Lib source code but I don't know what it is for.

我认为它用于限制模块的可访问成员.因此，当dir(module)时，仅显示__all__处的元素.

I thought it was used to limit accessible members of of a module. So only the elements at __all__ will show up when dir(module).

我做了一个小例子，发现它没有按我预期的那样工作.

I did a little example and saw it was not working as I expected.

那么... python __all__模块级别的变量是做什么用的?

So... What's the python __all__ module level variable for?

推荐答案

它有两个用途:

1. 任何阅读源代码的人都会知道公开的公共API是什么.它不会阻止阻止它们进入私有声明中，但确实提供了一个很好的警告.

1. Anybody who reads the source will know what the exposed public API is. It doesn't prevent them from poking around in private declarations, but does provide a good warning not to.

使用from mod import *时，仅导入__all__中列出的名称.我认为这并不重要，因为导入所有内容都是一个真正坏主意.

When using from mod import *, only names listed in __all__ will be imported. This is not as important, in my opinion, because importing everything is a really bad idea.

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