[Python-Dev] Implementing File Modes

[MRAB]

Paul Moore wrote:
> 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.
> 
What about stderr? You could add "e" if you want to read from it.