Python cannot import name <class>

Question

I've been wrestling most of the night trying to solve an import error.

This is a common issue, but no previous question quite answers my issue.

I am using PyDev (an Eclipse plugin), and the library Kivy (a Python library)

I have a file structure set up like this:

<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.

The files look like this:

main.py

# main.py
from code.engine import Engine

class MotionApp(App):
    # Ommited

engine.py

# engine.py
from code.main_menu_widget import MainMenuWidget

class Engine():
    # Ommited

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:

 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....

Possible duplicate of ImportError: Cannot import name X

Baum mit Augen
– Baum mit Augen ♦

2016-05-18 16:32:57 +00:00
Commented May 18, 2016 at 16:32 — Baum mit Augen
– Baum mit Augen ♦, Commented May 18, 2016 at 16:32

Gaurav Kumar · Accepted Answer · 2015-11-02 09:42:15Z

13

There seems to be a circular import. from engine.py you are importing main_menu_widget while from main_menu_widgetyou are importing engine.

That is clearly a circular import which is not allowed by python.

answered Nov 2, 2015 at 9:42

Gaurav Kumar

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Comments

Brian Dilley · Accepted Answer · 2013-03-04 03:17:25Z

5

it's in the same folder, use a relative package name (it's a good practice to do so anyway):

from .engine import Engine

answered Mar 4, 2013 at 3:17

Brian Dilley

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6 Comments

MintyAnt Over a year ago

not code.engine? Wouldnt that make more sense, since it's all inside a root "code" package?

Brian Dilley Over a year ago

It's generally a good practice to use relative imports when importing things from your own project.

MintyAnt Over a year ago

Fair enough. I just tried it, no luck, it throws the same error, same line. "cannot import name Engine"

Brian Dilley Over a year ago

oh, duh - you have a circular dependency, main_menu_widget.py depends on engine.py and vica verca

MintyAnt Over a year ago

Yep, that's a circular dependency. It's a shitty singleton too. Thanks, I posted a new question for this, but did find a way to bypass. Wish the error message was a tad more descriptive! stackoverflow.com/questions/15216424/…

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Nicola Musatti · Accepted Answer · 2013-05-22 09:20:31Z

1

Your code directory is a package. Ensure that the directory above it, i.e C:\MyProject judging from your error messages, is in your PYTHONPATH.

Open the context menu by selecting your project and clicking your mouse's right button, then select Properties. Select PyDev - PYTHONPATH and from there the Source folders tab. Check that the directory mentioned above is present; if it isn't press Add source folder, select it from the dialogue and press OK.

answered May 22, 2013 at 9:20

Nicola Musatti

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