Python 无法导入名称 <class>
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Python cannot import name <class>
提问by MintyAnt
I've been wrestling most of the night trying to solve an import error.
我整晚都在努力解决导入错误。
This is a common issue, but no previous question quite answers my issue.
这是一个常见问题，但之前的问题都没有完全回答我的问题。
I am using PyDev (an Eclipse plugin), and the library Kivy (a Python library)
我正在使用 PyDev（一个 Eclipse 插件）和库 Kivy（一个 Python 库）
I have a file structure set up like this:
我有一个这样设置的文件结构：
<code>
__init__.py
main.py
engine.py
main_menu_widget.py
"code" is held within the eclipse folder "MyProject" but it's not a package so I didn't include it.
“代码”保存在 eclipse 文件夹“MyProject”中，但它不是一个包，所以我没有包含它。
The files look like this:
文件如下所示：
main.py
主文件
# main.py
from code.engine import Engine
class MotionApp(App):
# Ommited
engine.py
引擎.py
# engine.py
from code.main_menu_widget import MainMenuWidget
class Engine():
# Ommited
main_menu_widget.py
main_menu_widget.py
# main_menu_widget.py
from code.engine import Engine
class MainMenuWidget(Screen):
pass
The error I recieve, in full detail, is:
我收到的错误详细信息是：
Traceback (most recent call last):
File "C:\MyProject\code\main.py", line 8, in <module>
from code.engine import Engine
File "C:\MyProject\code\engine.py", line 6, in <module>
from code.main_menu_widget import MainMenuWidget
File "C:\MyProject\code\main_menu_widget.py", line 3, in <module>
from code.engine import Engine
Any idea what I did wrong here? I just renamed my entire folder structure because I screwed up this module structure so bad, but I think i'm close to how it should look....
知道我在这里做错了什么吗？我刚刚重命名了我的整个文件夹结构，因为我把这个模块结构搞砸了，但我想我已经接近它应该是什么样子了......
回答by Brian Dilley
it's in the same folder, use a relative package name (it's a good practice to do so anyway):
它在同一个文件夹中，使用相对包名称（无论如何这样做是一个好习惯）：
from .engine import Engine
回答by Nicola Musatti
Your code directory isa package. Ensure that the directory above it, i.e C:\MyProjectjudging from your error messages, is in your PYTHONPATH.
您的代码目录是一个包。确保它上面的目录，即C:\MyProject根据您的错误消息判断，在您的 PYTHONPATH 中。
Open the context menu by selecting your project and clicking your mouse's right button, then select Properties. Select PyDev - PYTHONPATHand from there the Source folderstab. Check that the directory mentioned above is present; if it isn't press Add source folder, select it from the dialogue and press OK.
通过选择您的项目并单击鼠标右键打开上下文菜单，然后选择Properties。选择PyDev - PYTHONPATH，然后选择Source folders选项卡。检查上面提到的目录是否存在；如果不是按Add source folder，从对话框中选择它并按OK。
回答by Gaurav Kumar
There seems to be a circular import.
from engine.pyyou are importing main_menu_widgetwhile from main_menu_widgetyou are importing engine.
似乎有一个循环导入。from engine.pyyou are importing main_menu_widgetwhile from main_menu_widgetyou are importing engine.
That is clearly a circular import which is not allowed by python.
这显然是 python 不允许的循环导入。
