在Python中，是“来自Module import ClassName”的成语“典型？ [英] In Python, is the idiom "from Module import ClassName" typical?

问题描述

由于我更喜欢​​小文件，我通常会为每个Python模块放置一个公共类。我将模块命名为与其包含的类相同的名称。例如，类 ToolSet 将在 ToolSet.py 中定义。

Since I prefer small files, I typically place a single "public" class per Python module. I name the module with the same name as the class it contains. So for example, the class ToolSet would be defined in ToolSet.py.

在一个包中，如果另一个模块需要实现类ToolSet的对象，我使用：

Within a package, if another module needs to instanciate an object of class ToolSet, I use:

from ToolSet import ToolSet
...
toolSet = ToolSet()

而不是：

import ToolSet
...
toolSet = ToolSet.ToolSet()

我这样做是为了减少口吃（我更喜欢在文件顶部比在我的代码中口吃。）

I do this to reduce "stutter" (I prefer to have stutter at the top of the file than within my code.)

这是一个正确的习语吗？

Is this a correct idiom?

这是一个相关的问题。在一个软件包中，我经常会有一些我希望向外界展示的课程。这些我导入该包的 __ init __。py 。例如，如果 ToolSet 在包 UI 中，我想公开它，我会在<$中添加以下内容c $ c> UI / __ init __。py ：

Here is a related question. Within a package, I often have a small number of classes that I would like to expose to the outside world. These I import inside the __init__.py for that package. For example, if ToolSet is in package UI and I want to expose it, I would put the following in UI/__init__.py :

from ToolSet import ToolSet

因此，从外部模块我可以写

So that, from an external module I can write

import UI
...
toolSet = UI.ToolSet()

再次，这是pythonic吗？

Again, is this pythonic?

推荐答案

回答你的第一个问题，这就是我用的习语， PEP8蟒蛇风格指南支持其使用

To answer your first question, that is the idiom I use, and its use is supported by PEP8 the python style guide

可以这样说：

it's okay to say this though:

来自子流程导入Popen，PIPE

from subprocess import Popen, PIPE

我喜欢它，因为它减少了输入并确保文件运行时出现问题（比如拼写错误的导入）而不是一段时间后，当一个函数使用g导入运行。

I like it as it reduces typing and makes sure that things go wrong immediately the file is run (say you mis-spelt an import) rather than some time later when a function using the import is run.

例如假设模块 Thing 没有 Thyng 会员

from Thing import Thyng

运行 .py 文件后立即出错，而

Goes wrong immediately you run the .py file, whereas

import Thing
# ...
def fn():
    Thing.Thyng()

在运行 fn（）

关于你的第二个问题，我认为这也是一个好习惯。当我将一个large.py分解为一个带有 __ init __。py 和实现文件的目录时，我经常会遇到这种情况。将内容导入 __ init __。py 可使界面保持不变。这也是标准库中的常见做法。

As for your second question, I think that is also good practice. It often happens to me when I factor a single large.py into a directory with an __init__.py and implementation files. Importing things into the __init__.py keeps the interface the same. It is common practice in the standard libraries too.

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