Description
Running python3 -m websockets wss://echo.websocket.org/ on Python 3.8.5 gives an uninformative error:
Traceback (most recent call last):
File "/usr/lib/python3.8/runpy.py", line 194, in _run_module_as_main
return _run_code(code, main_globals, None,
File "/usr/lib/python3.8/runpy.py", line 87, in _run_code
exec(code, run_globals)
File "/home/$USER/websockets/src/websockets/__main__.py", line 215, in <module>
main()
File "/home/$USER/websockets/src/websockets/__main__.py", line 181, in main
async def queue_factory() -> asyncio.Queue[str]:
TypeError: 'type' object is not subscriptable
The issue is related to the PEP 585 - Type Hinting Generics In Standard Collections, which is introduced in Python 3.9.
This does not fit the Python version requirement specified in the documentation.
The fix could be either:
- quoting the
asyncio.Queue[str]on the line 181 of__main__.py, or - importing
from __future__ import annotationsthe backwards compatility.
NOTE: If the latter fix is chosen, I think it would be style-consistent to convert other quoted type hints (on lines 94 and 95) to type-hinted generics.
I have submitted a PR with the latter fix.