如何解决“ ValueError：尝试相对顶级包进行相对导入”

Question

I have the following problem with my project, help me please! Here is the structure of my package:

/pkg

/pkg/__init__.py
/pkg/sub1/__init__.py
/pkg/sub2/__init__.py

/pkg/sub1/foo1.py
/pkg/sub2/foo2.py

Here is implementation of foo1.py:

from ..sub2 import foo2

def f():
    print("Hello!")

When I run foo1 I get error: ValueError: attempted relative import beyond top-level package .

I can solve it doing the following adjustment:

import sys
import os
sys.path.append(os.path.abspath(os.path.pardir))

from sub2 import foo2
def f():
    print("Hello!")

But I wonder if there is a way to do it without importing sys and appending parent directory in it.

I heard that if I had .py file '/pkg/start.py' for example which called my foo1 module, then two dots would work. However, is there any way to call foo2 from foo1 directly?

Answer 1

It seems to me, that without adding pkg to my PATH it is impossible to import modules from sub2 in sub1. Here is explanation why:

Relative imports use a module's name attribute to determine that module's position in the package hierarchy. If the module's name does not contain any package information (eg it is set to ' main ') then relative imports are resolved as if the module were a top level module, regardless of where the module is actually located on the file system.

Here is official python web site, where it is explained