应该使用`import os.path`还是`import os`？ [英] Should I use `import os.path` or `import os`?

问题描述

根据官方文档， os .path 是一个模块。因此，导入它的首选方式是什么？

According to the official documentation, os.path is a module. Thus, what is the preferred way of importing it?

# Should I always import it explicitly?
import os.path

或...

# Is importing os enough?
import os

请不要回答import os 为我工作。我知道，它适用于我现在（从Python 2.6）。我想知道的是关于这个问题的任何官方建议。因此，如果您回答此问题，请发布您的参考。

Please DON'T answer "importing os works for me". I know, it works for me too right now (as of Python 2.6). What I want to know is any official recommendation about this issue. So, if you answer this question, please post your references.

推荐答案

os.path 以有趣的方式工作。看起来 os 应该是一个包含子模块 path 的包，但实际上 os 是一个正常的模块，用 sys.modules 来注入 os.path 下面是发生了什么：

os.path works in a funny way. It looks like os should be a package with a submodule path, but in reality os is a normal module that does magic with sys.modules to inject os.path. Here's what happens:

• 当Python启动时，它将一组模块加载到 sys.modules 。它们不会绑定到脚本中的任何名称，但是当您以某种方式导入时，可以访问已创建的模块。

• When Python starts up, it loads a bunch of modules into sys.modules. They aren't bound to any names in your script, but you can access the already-created modules when you import them in some way.

• sys.modules 是模块被高速缓存的dict。当你导入一个模块，如果它已经被导入到某个地方，它会得到实例存储在 sys.modules 。

• sys.modules is a dict in which modules are cached. When you import a module, if it already has been imported somewhere, it gets the instance stored in sys.modules.

os 是Python启动时加载的模块之一。它将路径属性分配给特定于os的路径模块。

os is among the modules that are loaded when Python starts up. It assigns its path attribute to an os-specific path module.

c> sys.modules ['os.path'] = path ，以便您可以执行 import os.path 它是一个子模块。

It injects sys.modules['os.path'] = path so that you're able to do "import os.path" as though it was a submodule.

我倾向于认为 os.path 作为一个我想使用的模块，而不是 os 模块不是真的一个子模块的 os ，我导入它喜欢它是一个和我总是做 import os.path 。这与如何记录 os.path 是一致的。

I tend to think of os.path as a module I want to use rather than a thing in the os module, so even though it's not really a submodule of a package called os, I import it sort of like it is one and I always do import os.path. This is consistent with how os.path is documented.

顺便说一下，这种结构导致很多Python程序员早期对模块和包和代码组织的困惑，我想。这真的有两个原因

Incidentally, this sort of structure leads to a lot of Python programmers' early confusion about modules and packages and code organization, I think. This is really for two reasons

1. 如果你认为 os 一个包，并知道你可以做 import os ，并且可以访问子模块 os.path ，你可能会感到惊讶稍后当您无法导入 import twisted 并自动访问 twisted.spread ，而无需导入。

1. If you think of os as a package and know that you can do import os and have access to the submodule os.path, you may be surprised later when you can't do import twisted and automatically access twisted.spread without importing it.

令人困惑的是， os.name 是一个正常的东西，一个字符串和 os。 path 是一个模块。我总是用空的 __ init __。py 文件来结构我的包，所以在同一级别我总是有一种类型的东西：一个模块/包或其他东西。几个大型Python项目采用这种方法，这倾向于制作更多的结构化代码。

It is confusing that os.name is a normal thing, a string, and os.path is a module. I always structure my packages with empty __init__.py files so that at the same level I always have one type of thing: a module/package or other stuff. Several big Python projects take this approach, which tends to make more structured code.

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