[Python-Dev] Implementing File Modes

[Paul Moore]

2009/7/27 Eric Pruitt <eric.pruitt at gmail.com>:
> Hello,
>
> Since there was a bit of confusion last time, I'll start by saying I am
> working on the subprocess.Popen module for Google Summer of Code. One of the
> features I am implementing is a class so that a running process can stand in
> in place of a file. For examples, instead of open( "filelist", mode = 'r')
> one would call ProcessIOWrapper( "ls -l", mode = 'r'). I am trying to decide
> if I should fully implement the mode argument. Right now, it essentially
> ignores everything but a 'U' indicated universal newlines in the mode
> argument. Should I leave that as is or make it so that things like "r+",
> "w", "a" are handled the way they would be for an actual file?

I would expect "r" to produce a pipe that reads from stdout of the
subprocess, and "w" to produce a pipe that writes to stdin of the
subprocess. "a" would be the same as "w", and arguably "r+" would be a
bidirectional pipe - read from the subprocess stdout and write to its
stdin.

I'd be OK with "r+" not being implemented (if it's too hard to avoid
deadlocks) but "r" and "w" should be present.

Paul.