了解模块和绝对/相对包导入

Question

I have created a package containing sub-folders and I would like to include a parent module from a sub-package module .

I have tried to follow the project structure suggested here https://docs.python-guide.org/writing/structure/ and attempted to replicate the step-by-step procedure as listed here http://zetcode.com/lang/python/packages/ but it seems that I am missing something obvious about python's package system

Here's my project structure

watches/
-- ...
-- watches/
---- __init__.py (empty)
---- Logger.py
---- main.py
---- db/
------ __init__.py (empty)
------ EntryPoint.py

Logger.py contains a single class :

class Logger:
   ...

I try to import Logger.py's class and methods from db/EntryPoint.py as follow :

from watches.Logger import Logger
class EntryPoint: 
   ...

Then, I want to wrap-up everything in main.py as follow:

from db.EntryPoint import EntryPoint

if __name__ == "__main__":
    t = EntryPoint("local")

and finally, when I try to execute main.py as follow python3 main.py (so I am located in watches/watches directory as you can guess), I guet the following error stack trace :

Traceback (most recent call last):
  File "main.py", line 1, in <module>
    from db.EntryPoint import EntryPoint
  File "some/absolute/path/watches/watches/db/EntryPoint.py", line 4, in <module>
    from watches.Logger import Logger
ModuleNotFoundError: No module named 'watches'

Answer 1

Every import will be relative to the location where the script is being run, in your case, main.py.

So, the point of view of your program is:

-logger.py
-__init__.py
-db/
---__init__.pt
---EntryPoint.py

The program is not aware that he is an module called watches, so if you want to import the logger.py in your main, simply do:

from Logger import Logger

Or move your main to the parent folder.