从包内的父目录导入模块

Question

I've referred to several threads and articles including:

• Importing modules from parent folder
• Can't get Python to import from a different folder
• Import Script from a Parent Directory
• PEP 328 -- Imports: Multi-Line and Absolute/Relative

but can't get the desired result.

Say I have a directory called "helloworld":

helloworld
|--__init__.py
|--say_hello.py
|--another_hello
   |--__init__.py
   |--import_hello.py

This is say_hello.py:

def hello_world():
    print("Hello World!")
if __name__ == "__main__":
    hello_world()

This is import_hello.py:

from .. import say_hello
say_hello.hello_world()

I am hoping to import say_hello module wherever I call python /path/to/import_hello.py without using sys module .

However, now when I do python /path/to/import_hello.py , it will return ValueError: attempted relative import beyond top-level package , and I have no idea why it isn't working.

Even this doesn't work:

from helloworld import say_hello
say_hello.hello_world()

It will give me ModuleNotFoundError: No module named 'helloworld' .

Answer 1

You can't run a script out of the middle of a package like that. When you do that, you're not running helloworld.another_hello.import_hello based out of /path/to/helloworldsparent/ , you're running __main__ based out of /path/to/helloworldsparent/helloworld/another_hello . So, it doesn't have a parent package to import as .. .

---

You can run the module with -m :

$ python -m helloworld.another_hello.import_hello

… assuming helloworld 's directory is on your sys.path (eg, because you've installed it into site-packages , or because your current working directory is its parent, or because you've set up a PYTHONPATH ).

---

But a cleaner solution is usually to leave the deep modules alone and write "entry point" scripts at the top level that look like this:

import helloworld.another_hello.import_hello
helloworld.another_hello.import_hello.main()

If you're using setuptools (and you really should be for anything complicated enough to need two levels of packages), you can make it create the entry point scripts automatically at install time (or at --inplace time, during development). See Automatic Script Creation in the docs (but you're probably going to need to read other sections as well to get the whole idea; the docs are pretty large and complicated).

Answer 2

I feel you can first try to add the parent path to the system path and then try using the import.

from sys import path as pylib
import os
pylib += os.path.abspath('..')
from helloworld import say_hello

Hope it helps !!