[Python] How to import an editable package?

I've installed a package from a cloned repository, in "editable" mode (pip install -e .). I can't import the package in a script in the virtual environment where the package in installed (the import cannot be resolved).

What I did:

1. 
   venv .venv and activate it
   
   
2. 
   git clone https://github.com/rm-hull/luma.lcd.git
   
   
3. 
   python -m pip install -e ./luma.lcd
   
   
4. 
   Create a test.py file in the root dir and try to import luma.lcd
   

Importing luma.lcd gives an error. luma.core, a (non-editable) dependency of luma.lcd can be imported without a problem.

The directory structure is:

.
├── luma.lcd
│ ├── luma
│ │ └── lcd
│ │ └── (…)
│ └── luma.lcd.egg-info
├── test.py
└── .venv
└── lib
└── python3.11
└── site-packages
└── luma
└── core
├── __editable___luma_lcd_2_11_0_finder.py
└── __editable__.luma_lcd-2.11.0.pth


The file __editable___luma_lcd_2_11_0_finder.py contains:

from __future__ import annotations
import sys
from importlib.machinery import ModuleSpec, PathFinder
from importlib.machinery import all_suffixes as module_suffixes
from importlib.util import spec_from_file_location
from itertools import chain
from pathlib import Path

MAPPING: dict[str, str] = {'luma': '/home/user/luma/luma.lcd/luma'}
NAMESPACES: dict[str, list[str]] = {'luma': ['/home/user/luma/luma.lcd/luma']}
PATH_PLACEHOLDER = '__editable__.luma_lcd-2.11.0.finder' + ".__path_hook__"


class _EditableFinder: # MetaPathFinder
@classmethod
def find_spec(cls, fullname: str, path=None, target=None) -> ModuleSpec | None: # type: ignore
# Top-level packages and modules (we know these exist in the FS)
if fullname in MAPPING:
pkg_path = MAPPING[fullname]
return cls._find_spec(fullname, Path(pkg_path))

# Handle immediate children modules (required for namespaces to work)
# To avoid problems with case sensitivity in the file system we delegate
# to the importlib.machinery implementation.
parent, _, child = fullname.rpartition(".")
if parent and parent in MAPPING:
return PathFinder.find_spec(fullname, path=[MAPPING[parent]])

# Other levels of nesting should be handled automatically by importlib
# using the parent path.
return None

@classmethod
def _find_spec(cls, fullname: str, candidate_path: Path) -> ModuleSpec | None:
init = candidate_path / "__init__.py"
candidates = (candidate_path.with_suffix(x) for x in module_suffixes())
for candidate in chain([init], candidates):
if candidate.exists():
return spec_from_file_location(fullname, candidate)
return None


class _EditableNamespaceFinder: # PathEntryFinder
@classmethod
def _path_hook(cls, path) -> type[_EditableNamespaceFinder]:
if path == PATH_PLACEHOLDER:
return cls
raise ImportError

@classmethod
def _paths(cls, fullname: str) -> list[str]:
paths = NAMESPACES[fullname]
if not paths and fullname in MAPPING:
paths = [MAPPING[fullname]]
# Always add placeholder, for 2 reasons:
# 1. __path__ cannot be empty for the spec to be considered namespace.
# 2. In the case of nested namespaces, we need to force
# import machinery to query _EditableNamespaceFinder again.
return [*paths, PATH_PLACEHOLDER]

@classmethod
def find_spec(cls, fullname: str, target=None) -> ModuleSpec | None: # type: ignore
if fullname in NAMESPACES:
spec = ModuleSpec(fullname, None, is_package=True)
spec.submodule_search_locations = cls._paths(fullname)
return spec
return None

@classmethod
def find_module(cls, _fullname) -> None:
return None


def install():
if not any(finder == _EditableFinder for finder in sys.meta_path):
sys.meta_path.append(_EditableFinder)

if not NAMESPACES:
return

if not any(hook == _EditableNamespaceFinder._path_hook for hook in sys.path_hooks):
# PathEntryFinder is needed to create NamespaceSpec without private APIS
sys.path_hooks.append(_EditableNamespaceFinder._path_hook)
if PATH_PLACEHOLDER not in sys.path:
sys.path.append(PATH_PLACEHOLDER) # Used just to trigger the path hook


sys.path returns:

['', '/usr/lib/python311.zip', '/usr/lib/python3.11', '/usr/lib/python3.11/lib-dynload', '/home/user/luma/.venv/lib/python3.11/site-packages', '__editable__.luma_lcd-2.11.0.finder.__path_hook__']

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