Does Blender text editor not support custom module importing?

Question

In VSC, this code works

import bpy
from subp.panel import Panel

Panel.test()

However, in the Blender text editor, Suddenly it doesn't work

ModuleNotFoundError: No module named 'subp'

If I change the second line to from .subp.panel import Panel then

ImportError: attempted relative import with no known parent package

Why can't I run the code in the blender text editor like this?

When I move the panel.py to the outside of the subp folder and change to from .panel import Panel, it throws the same error

ImportError: attempted relative import with no known parent package

Answer 1

EDIT: Hopefully clearer answer in response to comments.

The short answer is 'No, you can't do that'.

The long answer

The reason this works in VSC is that Python has a system variable called PYTHONPATH. Python searches all of the directories in PYTHONPATH to find the file. VSC knows this and adds the directory containing your module to PYTHONPATH.

For various reasons, Blender ignores PYTHONPATH by default. So it can't find modules that VSC can.

The workaround

You can work around this by

• running Blender with the command line argument --python-use-system-env and
• Adding the parent directory of your module to the search path using code along the lines of

import sys
sys.path.append("PATH_TO_YOUR_MODULE")

before you try to import it. That's only the path to the directory containing the module. Don't include the module name.

Background

You may want to read the Python manual section on the import system; especially the paragraph about searching. The key bit has to do with import path

A list of locations (or path entries) that are searched by the path based finder for modules to import. During import, this list of locations usually comes from sys.path, but for subpackages it may also come from the parent package’s path attribute.

For a discussion of Blender and PYTHONPATH, see this answer