[ENG-4134]Allow specifying custom app module in rxconfig

[ElijahAhianyo]

import sys
import reflex as rx
from pathlib import Path


sys.path.insert(0, str(Path("/path/to/app/foo/")))

config = rx.Config(
    app_name="my_project",
    app_module_path="foo.foo"
)

Assuming you have a reflex app foo with App instance living in foo/foo/foo.py

Example app: reflex-dev/reflex-examples#291

[linear]

ENG-4134 Allow specifying app instance in rxconfig.py

[ElijahAhianyo]

wondering if this is what we should be doing. Or should we return the absolute path here? Im trying to think of where doing it like this could pose a real problem

[ElijahAhianyo]

integration tests need reflex-dev/reflex-examples#291 to pass

[masenf]

i don't like the assumption that the pythonpath entry is module_path.parent.parent.

i think a better approach would make the caller responsible for setting their sys.path / PYTHONPATH, and then providing an importable name.

That would save us this complicated import machinery that makes assumptions that would be hard to undo later, we could just use __import__, like we have been.

[masenf]

i think for this one, we should go up the parent directories until we don't find an __init__.py, this should be the root of the reload dir for an out-of-tree app module.

[masenf]

updated by comment from before. i realize we can't actually instantiate an rx.App from inside rxconfig.py because app initialization depends on getting the config

[masenf]

@ElijahAhianyo i opened a PR into your branch #4644 for your review

[ElijahAhianyo]

@masenf I think we need reflex-dev/reflex-examples#291 merged to pass the CI and then it's ready to go