import of undeclared dependency "aiohttp" is attempted even if AsyncClient is not required - Githubissues

madpilot / pyptv3

Access the Public Transport Victoria API with Python 3

MIT License

7 stars 0 forks source link

import of undeclared dependency "aiohttp" is attempted even if AsyncClient is not required #2

Open Lx opened 5 years ago

Lx commented 5 years ago

Background

The pyptv3 package offers both blocking and non-blocking clients: Client & AsyncClient.
Since use of AsyncClient is optional, the pyptv3 package correctly does not declare aiohttp as an installation dependency.

Problem

When importing pyptv3 without the intention of using the non-blocking AsyncClient, attempt to import aiohttp still occurs.

If aiohttp is not installed, problems arise:

import pyptv3
Traceback (most recent call last):
File "pyptv3/__init__.py", line 2, in <module>
  from .async_client import AsyncClient
File "pyptv3/async_client.py", line 2, in <module>
  import aiohttp
ModuleNotFoundError: No module named 'aiohttp'

Expectation

Import of aiohttp should only be attempted if pyptv3.AsyncClient is imported directly.
import pyptv3, which occurs when non-blocking AsyncClient support is not needed, should not cause pyptv3.AsyncClient to be imported.
aiohttp should remain an optional dependency as it is now.

Workaround until issue is resolved

Install aiohttp dependency manually alongside pyptv3 even if AsyncClient support is not needed.

Environment

$ pip -V
pip 19.0.3 from /.../pip-19.0.3-py3.7.egg/pip (python 3.7)
$ pip show pyptv3 | grep Version:
Version: 0.0.4

Lx commented 5 years ago

On further reflection, the AsyncClient might be better off in a separate PyPI package (perhaps pyptv3-asyncio?) which can depend on pyptv3 and any asyncio-related dependencies.

Then projects depending on AsyncClient could specify pyptv3 and pyptv3-asyncio as dependencies and have correct access to everything without ImportErrors.