fix: library stub not found

[SaidBySolo]

Summary

# sample.py
from discord import app_commands

app_commands.command()

When I check the file with mypy, it says that the stub cannot be found.

discord\app_commands\commands.py:89: error: Cannot find implementation or library stub for module named "discord.ext.commands"

#7743 (comment)
Perhaps it has something to do with the issue comment.

Checklist

• If code changes were made then they have been tested.
  • I have updated the documentation to reflect the changes.
• This PR fixes an issue.
• This PR adds something new (e.g. new method or parameters).
• This PR is a breaking change (e.g. methods or parameters removed/renamed)
• This PR is not a code change (e.g. documentation, README, ...)

[mikeshardmind]

I can't reproduce the issue this intends to fix with pyright, with mypy...

(.venv) PS > Get-Content .\scratch.py

import discord
from discord import app_commands


@app_commands.command()
async def test(interaction: discord.Interaction):
    ...
(.venv) PS > mypy --namespace-packages .\scratch.py 
Success: no issues found in 1 source file

You might need to add namespace-packages to your mypy config

(.venv) PS > mypy --no-namespace-packages .\scratch.py    
.venv\lib\site-packages\discord\app_commands\commands.py:72: error: Cannot find implementation or library stub for module named "discord.ext.commands"
.venv\lib\site-packages\discord\app_commands\commands.py:72: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
Found 1 error in 1 file (checked 1 source file)

which is something the error actually points you to

[SaidBySolo]

sample/
├─ __init__.py
├─ main.py

# main.py
import discord
from discord import app_commands

@app_commands.command()
async def main(interaction: discord.Interaction) -> None:
    ...

mypy ./sample --strict

This is a reproducible example.

Looking at #8327, I personally think this is not an ideal import.

[mikeshardmind]

As pointed out previously, you can resolve this as a configuration change. mypy supports changing the behavior of import discovery. Trimming what I had above to only what's needed to show that, and including the error from mypy which also informed you of this:

(.venv) PS > mypy --strict --namespace-packages .\scratch.py 
Success: no issues found in 1 source file

vs

(.venv) PS > mypy --strict .\scratch.py
.venv\lib\site-packages\discord\app_commands\commands.py:72: error: Cannot find implementation or library stub for module named "discord.ext.commands"
.venv\lib\site-packages\discord\app_commands\commands.py:72: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
Found 1 error in 1 file (checked 1 source file)

[SaidBySolo]

@mikeshardmind
I don't like changing the configuration of my mypy because of one discord.py.

Are there any problems with these code changes?

[mikeshardmind]

I don't like changing the configuration of my mypy because of one discord.py.

mypy's error there literally tells you to do this if this is the reason for it not detecting the import, see the link in the error message. Beyond this, you can change it on a per-package basis. you don't need to change the behavior globally.

Are there any problems with these code changes?

Possibly (such as inconsistencies in import, churn for no tangible gain, etc) but I wasn't exactly reviewing the code, just pointing out that this shouldn't be an issue.

[SaidBySolo]

In my opinion, considering the issues mentioned above, I think these changes are meaningful changes to maintain consistency.

[Rapptz]

Thanks. Though I can't make any promises that I'll care about this for internal code. My comment pertained to external code. What @mikeshardmind said is correct, considering discord.py makes extensive use of namespace packages you need to enable the feature for it to work as expected on mypy.

[richfromm]

Fwiw, I am able to reproduce this problem with discord.py 2.0.1 and mypy 0.982 and python 3.10.7, but in a bizarre way, it alternates between failing and passing:
bryanforbes/discord.py-stubs#171 (comment)
bryanforbes/discord.py-stubs#171 (comment)

But from inspection (only) I'm wondering if the fix is correct or not:
e196167#r86069248
e196167#r86069343

[Rapptz]

Are you running mypy with --namespace-packages?