[Python-ideas] Tulip / PEP 3156 (original) (raw)

[Python-ideas] Tulip / PEP 3156 - subprocess events

Paul Moore p.f.moore at gmail.com
Tue Jan 22 13:03:43 CET 2013

On 19 January 2013 12:12, Paul Moore <p.f.moore at gmail.com> wrote:

I would love for you to create that version. I only checked it in so I could point to it -- I am not happy with either the implementation, the API spec, or the unit test... May be a few days before I can get to it.

OK, I finally have a working VM.

The subprocess test code assumes that it can call transport.write_eof() in the protocol connection_made() function. I'm not sure if that is fundamental, or just an artifact of the current implementation. Certainly if you have a stdin pipe open, you likely want to close it to avoid deadlocks, but with the subprocess.Popen approach, it's entirely possible to not open a pipe to stdin. In that case, writing to stdin is neither possible nor necessary.

Clearly, writing data to stdin if you didn't open a pipe should be flagged as an error. And my immediate thought is that write_eof should also be an error. But I can imagine people wanting to write reusable protocols that pre-emptively write EOF to the stdin pipe to avoid deadlocks.

So, a question: If the user passed a popen object without a stdin pipe, should write_eof be an error or should it just silently do nothing?

Paul

More information about the Python-ideas mailing list