[Python-ideas] Hooks into the IO system to intercept raw file reads/writes

[Paul Moore]

On 2 February 2015 at 17:47, Guido van Rossum <guido at python.org> wrote:
> Perhaps you would be better off using the subprocess machinery in asyncio?
> It uses the subprocess module to manage the subprocess itself (both for
> Windows and for Unix-ish systems) but uses the async I/O machinery from the
> asyncio module (which is itself based on select or its better brethren).

Quite possibly. I found the asyncio docs a bit of a struggle, TBH. Is
there a tutorial? The basic idea is something along the lines of
https://docs.python.org/3.4/library/asyncio-subprocess.html#subprocess-using-streams
but I don't see how I'd modify that code (specifically the "yield from
proc.stdout.readline()" bit) to get output from either stdout or
stderr, whichever was ready first (and handle the 2 cases
differently).

I don't know whether event-based behaviour makes more sense to me than
the corioutine-based approach used by the asyncio documentation. OTOH,
the alternative protocol-based approach didn't seem to have an event
for data received on stderr, just the one for stdout. So maybe it's
not just the approach that's confusing me.

Paul