Allow Path in create_subprocess_*

[Dreamsorcerer]

No description provided.

[srittau]

I am sorry for not checking earlier, but BaseEventLoop.subprocess_shell() and BaseEventLoop.subprocess_exec() check explicitly for the arguments to be str or bytes. (At least in Python 3.7.) Did you check that this works? Or are there other loop implementations that support this?

[Dreamsorcerer]

Huh, that's weird. I'm running this in Python 3.8:

proc = await asyncio.create_subprocess_exec(
    VAULT_PATH / "analytics.py", VAULT_KEY, WEB_CERT)

Also, for *args, I'm using Paths as in this code:

    proc = await asyncio.create_subprocess_exec(
        "openssl", "req", "-new", "-x509", "-newkey", "ec",
        ...
       "-nodes", "-out", cert_path, "-keyout", key_path)

I'm just using the default asyncio implementation in an aiohttp app.

[srittau]

It's possible that asyncio provides its own loops that support this. Could you add a comment to the two arguments to the effect that not all loops support PathLike arguments, just to clarify this?

[Dreamsorcerer]

OK, digging in a little closer, if you follow the function calls through here:
https://github.com/python/cpython/blob/232dda6cbc10860328a83517a6e3ea238ff4147f/Lib/asyncio/base_events.py#L1634
It appears to just pass the arguments to Popen.

That then converts the Path objects here:
https://github.com/python/cpython/blob/232dda6cbc10860328a83517a6e3ea238ff4147f/Lib/subprocess.py#L1350

However, it only does so if shell=False, so I was mistaken to add this to the shell version.

[Dreamsorcerer]

However, I see that there is an explicit check for str/bytes in the 3.7 branch. I'll make it conditional on 3.8 then.

[srittau]

Thanks!